I tried the nvidia-glx-180 package.
Thinking about it, I'll try a previous version, I didn't have any issues with Ubuntu 8.10 and the previous nvidia package (173, if I'm correct). Also, this is the first time I'm trying the 64 bit version.
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Update:
Just tried nvidia-glx-173, same issues. Disabled them and no problem

. I'd like to find out whether it's a driver issue (some bugs or problems with the 64 bit version) or some sympthoms of the
nVidia issues appearing again (last time I had the motherboard replaced since the nVidia chip is soldered to it)

.
Guess no "fancy effects" nor graphics intensive applications (I'm planning on doing some OpenGL programs) while I can find it out.
Any information/advice will be appreciated, thanks.