[CentOS] flash-plugin-9.0.124.0-1 having problems since firefox-3.0.7-3.el4.centos

Updated yesterday to the latest firefox from CentOS, and now RPMforge
flash-plugin will only play a few seconds of video (such as CNN,
iReport, etc.) at a time before becoming stuck; dragging the slider
back a little allows it to play a bit further, but then it stops
again.  YouTube plays the video without sticking, but has no sound.

glibc issues on el4 prevent upgrading to the newer flash-plugin or any
of the newer modules from the Adobe repo.

Has anyone else seen something like this?  I've had problems with the
sound device before on this machine, which occasionally caused flash
to get *entirely* stuck, so (based on no sound on YouTube) I'm going
to try rebooting to see if that may be a factor here; but I've never
had this particular symptom before.