oddities after update

i used synaptic to update today but now a couple of strange behaviors have popped up.

1) cube no longer works
2) shading windows is very slowing and choppy

I marked all upgrades and the upgrade went well. I rebooted and thought everything was good until I tried to use the cube.

Has anyone else experienced this? Is there a way to get these behaviors fixed?

Thank you so much.

jack

UPDATE: i just checked .xsession-errors and saw this line:

Checking for Xgl: not present. however nvidia-glx is install (according to synaptic).

why is the system no longer seeing glx?