Latest flash and old(er) video cards/chips is a nono.
Older versions:
11.1.102.63 working well on my Nvidia 8400GS and ATI 9600 Pro
10.3.183.19 doing the trick on Nvidia Riva TNT2, ATI Radeon and Rage, obscure older low mem video configs.
I replaced
as root
the libflashplayer.so
from /usr/lib/mozilla/plugins/
with the one from the archieved adobe .rpm files
With a Synaptic update with newer flash it will be overwritten,
so pinning of the last installed flash would protect your changes.
Be aware, using older versions could be a security risc.
Choose safe without watching flash, or watching flash with knowing you are in danger

Ed