irq event 5: bogus return value 19

["Professor Moriarty" <bofh.h4x@gmail.com>]

On debugging a soundcard driver (the Riptide driver from linuxant,
ported by me to 2.6), I seem to have 2 weird bugs that are giving me a
headache:
Both occur when I try to actually play a file
The first: ppos != &file->f_pos
If I comment that check out, I get a kernelpanic. If I comment out the
schedule_work() to run the bottom half of the IRQ handler, I get the
message:
irq event 5: bogus return value 19
Followed by:
kernel: Disabling IRQ #5
At this point, the first 4K of raw PCM plays, and then /dev/dsp
blocks, while the speakers repeat the 4K of data repeatedly until I
ctrl+C mplayer. Trying to cat data to /dev/dsp plays first 4K, then
cat says /dev/dsp is out of space.

Any ideas?

~ Vasily Ivanov