I've been running 12.10 for the longest time and was having what appeared to be video problems so opted to switch to NVIDIA drivers. Problems persisted so I upgraded to 13.04 but that didn't solve anything.

So... decided to give 13.10 a go and that's when things took a turn for the worse. I googled for answers and every purported fix I tried brought no joy. Then I read where someone could get a live CD of 13.10 to work but they ended having to do a complete reinstall with the Nouveau driver. That gave me hope.

I removed all the NVIDIA drivers using --purge and installed Nouveau but found no joy. To make a long story short, --purge does not remove the NVIDIA blacklist files from /etc/modprobe.d which were blacklisting the Nouveau driver.

Hopefully this saves someone from having to go through what I did.