@Gary, If a package is available in RPM format (Suse ,Mandriva ,Fedora ) , then
download it. You can install the 'alien' package & convert the RPM package to
Debian package!! As simple as that!!
$ sudo apt-get install alien
$ sudo alien <Package>.extension
like 'sudo alien package.rpm'
It will convert the RPM package to Debian automatically.
Also there seems to be a bug like @Prakash said. And it can be fixed
with a little patience.
Also run
glxgears from the Terminal Window
Check for any jerkiness.
See ScreenShot : Click
here