This problem is a known problem with old CPUs and newer flash player.. the solution is to downgrade the flash player.. but what Pjotr123 said , is correct.
I've keep the old version in my Ubuntu One account .. 11.1 (the newer version of flash is 11.2) for such cases..
The only thing you have to do is to copy the libflashplayer.so file to this path /usr/lib/mozilla/plugins/
Download the file from here => http://ubuntuone.com/0maDagKUuWihfc8A2ktnlp
and apply the commands below.. with order and one at time ( I assume you saved the file to Downloads folder)
As you can understand this is for i386 (32bit) Operating System.. If you have 64bit .. let me know.. and do not apply the commands above.
tar xvzf flashplayer11_1r102_63_linux.i386.tar.gz
sudo cp libflashplayer.so /usr/lib/mozilla/plugins/