Strange multimedia problem

[Marek Kozlowski]

:-)

Gentoo x86_64 stable with XFCE
adobe-flash -- tested with 10.2, 10.3 and 64-bit "square"
(unstable) Firefox 4.0.1

Sometimes (I can find any regularity) FF gets unable to play flash
videos (for example from YouTube) -- it starts jamming. It plays one
second and freezes for the next 3-4 secs. Once occurs the problem
persists. Restarting FF doesn't help. But: restarting XFCE usually
solves the problem.

I've checked running processes when FF's running -- nothing unusual;
after closing FF -- no extraneous ones are running -- only the system
ones and X and XFCE-ralated. Nothing more. Nothing to kill. I don't
think the problem is X-related. I tried a few versions of drivers and
the problem persists. Why does restarting XFCE help? What changes from
one session to other one?

Looks like some error occurs in some kind of cache, multimedia
architecture, some hal/udev/whatever or something similar that is wiped
out when XFCE session closes. GVFS? Such things are really difficult to
trace -- it's too multilayer for me. Any idea how can I try to debug it?

Best regards,
/M