i recently got a athlon64 3500 and installed linux on it
first kernel i put on it was 2.6.9-rc3-bk7 so im not sure
if any other kernels before this have the problem
but basicly the problem is with uhci-hcd and ehci-hcd
modules loaded and if you start a compile and
randomly sometime after that i get a kernel bug showing up in 
dmesg and it always seems to be due to cpudyn
or that is what is running when it happens not sure which
ive got a few errors saved and are below
these are from 2.6.9-rc4-bk1
motherboard is a 'k8t800 pro' chipset 939 socket (i wouldnt think
would make much diff tho)
i also have a skew in the clock perhaps its related
not sure how much its drifting but its alot
any other info needed ask away
ill attach the dmesg from the second error run
as its more complete
also it seems to need both usb hcd modules loaded
one or the other alone doesnt seem to trigger it

Unable to handle kernel NULL pointer dereference at 0000000000000091 RIP: 
<ffffffff80120f70>{do_page_fault+64}
PML4 1efed067 PGD 1ebb9067 PMD 0 
Oops: 0000 [1] PREEMPT 
CPU 0 
Modules linked in: ehci_hcd uhci_hcd r8169
Pid: 4945, comm: cpudynd Not tainted 2.6.9-rc4-bk1
RIP: 0010:[<ffffffff80120f70>] <ffffffff80120f70>{do_page_fault+64}
RSP: 0018:000001001f043578  EFLAGS: 00010016
RAX: ffffffff80120f30 RBX: 0000000000000001 RCX: ffffffff80121c63
RDX: 000fffff80399300 RSI: ffffffff80111250 RDI: 0000000000000000
RBP: 0000000000000091 R08: 0000000000000025 R09: 00000000002191c0
R10: 0000000000000004 R11: 0000000000000004 R12: 0000000000000000
R13: ffffffff80111250 R14: 000001001f606400 R15: 0000000000000000
FS:  0000002a958624a0(0000) GS:ffffffff80564840(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000091 CR3: 0000000000101000 CR4: 00000000000006e0
Process cpudynd (pid: 4945, threadinfo 000001001f042000, task 000001001ed55810)
Stack: 0000000000000000 0000000000000000 0000000000000000 0000010001b802f0 
       0000000000000000 0000010001b80298 0000000000000010 000001001fb79818 
       00000000000000a0 000001001f0ee558 
Call Trace:<ffffffff8010fb49>{error_exit+0}
<ffffffff80111250>{do_general_protection+0}
       <ffffffff80121c63>{search_extable+67}
<ffffffff80111266>{do_general_protection+22}
       <ffffffff802d6139>{scsi_prep_fn+873} <ffffffff8010fb49>{error_exit+0} 
       <ffffffff80121c63>{search_extable+67}
<ffffffff80121c63>{search_extable+67}
       <ffffffff80121c63>{search_extable+67}
<ffffffff80147b7d>{search_exception_tables+29}
       <ffffffff801112fd>{do_general_protection+173}
<ffffffff801327e0>{autoremove_wake_function+0}
       <ffffffff8010fb49>{error_exit+0} <ffffffff80238c1d>{vsnprintf+1277} 
       <ffffffff80238c1d>{vsnprintf+1277} <ffffffff80121c63>{search_extable+67} 
       <ffffffff80147b7d>{search_exception_tables+29}
<ffffffff8012129c>{do_page_fault+876}
       <ffffffff80130dcc>{finish_task_switch+108}
<ffffffff80394cee>{thread_return+41}
       <ffffffff8010fb49>{error_exit+0} <ffffffff80238c1d>{vsnprintf+1277} 
       <ffffffff80161c05>{do_no_page+1157} <ffffffff80238ca9>{vscnprintf+9} 
       <ffffffff801355e3>{vprintk+163} <ffffffff8015237a>{find_get_page+26} 
       <ffffffff8015313c>{filemap_nopage+396} <ffffffff801357ad>{printk+141} 
       <ffffffff803948bb>{schedule+235}
<ffffffff80142c80>{notifier_call_chain+32}
       <ffffffff80312d46>{cpufreq_notify_transition+358}
<ffffffff8011da34>{powernowk8_target+1012}
       <ffffffff8031390b>{__cpufreq_driver_target+27}
<ffffffff8031470b>{cpufreq_governor_performance+27}
       <ffffffff80313331>{__cpufreq_governor+129}
<ffffffff80313c72>{__cpufreq_set_policy+306}
       <ffffffff80313dde>{cpufreq_set_policy+78}
<ffffffff8031400b>{store_scaling_governor+139}
       <ffffffff80313d80>{handle_update+0}
<ffffffff8015664d>{__alloc_pages+189}
       <ffffffff80313271>{store+81} <ffffffff801ab912>{sysfs_write_file+178} 
       <ffffffff801718e7>{vfs_write+199} <ffffffff80171a23>{sys_write+83} 
       <ffffffff8010f296>{system_call+126} 

Code: f6 87 91 00 00 00 02 74 01 fb 8b 0d 98 9a 3c 00 85 c9 74 31 
RIP <ffffffff80120f70>{do_page_fault+64} RSP <000001001f043578>
CR2: 0000000000000091
 <6>note: cpudynd[4945] exited with preempt_count 1
bad: scheduling while atomic!

Call Trace:<ffffffff8039482e>{schedule+94}
<ffffffff801354f0>{release_console_sem+464}
       <ffffffff801607b6>{unmap_vmas+1510} <ffffffff8016545b>{exit_mmap+123} 
       <ffffffff80132b10>{mmput+128} <ffffffff801379d2>{do_exit+514} 
       <ffffffff8012140f>{do_page_fault+1247}
<ffffffff801ca5f5>{search_for_position_by_key+565}
       <ffffffff80111250>{do_general_protection+0}
<ffffffff8010fb49>{error_exit+0}
       <ffffffff80111250>{do_general_protection+0}
<ffffffff80120f30>{do_page_fault+0}
       <ffffffff80121c63>{search_extable+67}
<ffffffff80111250>{do_general_protection+0}
       <ffffffff80120f70>{do_page_fault+64} <ffffffff8010fb49>{error_exit+0} 
       <ffffffff80111250>{do_general_protection+0}
<ffffffff80121c63>{search_extable+67}
       <ffffffff80111266>{do_general_protection+22}
<ffffffff802d6139>{scsi_prep_fn+873}
       <ffffffff8010fb49>{error_exit+0} <ffffffff80121c63>{search_extable+67} 
       <ffffffff80121c63>{search_extable+67}
<ffffffff80121c63>{search_extable+67}
       <ffffffff80147b7d>{search_exception_tables+29}
<ffffffff801112fd>{do_general_protection+173}
       <ffffffff801327e0>{autoremove_wake_function+0}
<ffffffff8010fb49>{error_exit+0}
       <ffffffff80238c1d>{vsnprintf+1277} <ffffffff80238c1d>{vsnprintf+1277} 
       <ffffffff80121c63>{search_extable+67}
<ffffffff80147b7d>{search_exception_tables+29}
       <ffffffff8012129c>{do_page_fault+876}
<ffffffff80130dcc>{finish_task_switch+108}
       <ffffffff80394cee>{thread_return+41} <ffffffff8010fb49>{error_exit+0} 
       <ffffffff80238c1d>{vsnprintf+1277} <ffffffff80161c05>{do_no_page+1157} 
       <ffffffff80238ca9>{vscnprintf+9} <ffffffff801355e3>{vprintk+163} 
       <ffffffff8015237a>{find_get_page+26}
<ffffffff8015313c>{filemap_nopage+396}
       <ffffffff801357ad>{printk+141} <ffffffff803948bb>{schedule+235} 
       <ffffffff80142c80>{notifier_call_chain+32}
<ffffffff80312d46>{cpufreq_notify_transition+358}
       <ffffffff8011da34>{powernowk8_target+1012}
<ffffffff8031390b>{__cpufreq_driver_target+27}
       <ffffffff8031470b>{cpufreq_governor_performance+27} 
       <ffffffff80313331>{__cpufreq_governor+129}
<ffffffff80313c72>{__cpufreq_set_policy+306}
       <ffffffff80313dde>{cpufreq_set_policy+78}
<ffffffff8031400b>{store_scaling_governor+139}
       <ffffffff80313d80>{handle_update+0}
<ffffffff8015664d>{__alloc_pages+189}
       <ffffffff80313271>{store+81} <ffffffff801ab912>{sysfs_write_file+178} 
       <ffffffff801718e7>{vfs_write+199} <ffffffff80171a23>{sys_write+83} 
       <ffffffff8010f296>{system_call+126} 

and this was after a reboot or 2 i got this one:
----------- [cut here ] --------- [please bite here ] ---------
Kernel BUG at cpufreq:145
invalid operand: 0000 [1] PREEMPT 
CPU 0 
Modules linked in: snd_pcm_oss snd_pcm snd_timer snd_page_alloc
snd_mixer_oss snd usblp ehci_hcd uhci_hcd r8169
Pid: 5171, comm: cpudynd Not tainted 2.6.9-rc4-bk1
RIP: 0010:[<ffffffff80312bf6>] <ffffffff80312bf6>{cpufreq_notify_transition+22}
RSP: 0018:000001001e549c18  EFLAGS: 00010246
RAX: 00000000002191c0 RBX: 000001001e549c58 RCX: 0000000000000001
RDX: 0000000000000002 RSI: 0000000000000001 RDI: 000001001e549c58
RBP: 0000000000000001 R08: 0000000000000025 R09: 00000000002191c0
R10: 0000000000000004 R11: 0000000000000004 R12: 0000000000000002
R13: 000000000000000e R14: 000000000000000e R15: ffffffff80407530
FS:  0000002a958624a0(0000) GS:ffffffff80564840(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000005be0dc CR3: 0000000000101000 CR4: 00000000000006e0
Process cpudynd (pid: 5171, threadinfo 000001001e548000, task 000001001f0ce030)
Stack: 0000000000000000 0000010001a2ea80 0000000000000001 ffffffff8011da1b 
       000000000000000c 002191c000000002 000001001ff98200 0000000380239578 
       000f424000000000 00000100002191c0 
Call Trace:<ffffffff8011da1b>{powernowk8_target+987}
<ffffffff8031390b>{__cpufreq_driver_target+27}
       <ffffffff8031470b>{cpufreq_governor_performance+27} 
       <ffffffff80313331>{__cpufreq_governor+129}
<ffffffff80313c72>{__cpufreq_set_policy+306}
       <ffffffff80313dde>{cpufreq_set_policy+78}
<ffffffff8031400b>{store_scaling_governor+139}
       <ffffffff80313d80>{handle_update+0}
<ffffffff8015664d>{__alloc_pages+189}
       <ffffffff80313271>{store+81} <ffffffff801ab912>{sysfs_write_file+178} 
       <ffffffff801718e7>{vfs_write+199} <ffffffff80171a23>{sys_write+83} 
       <ffffffff8010f296>{system_call+126} 

Code: 0f 0b 98 b7 3c 80 ff ff ff ff 91 00 48 8b 05 57 9e 23 00 48 
RIP <ffffffff80312bf6>{cpufreq_notify_transition+22} RSP <000001001e549c18>