I didn't realize that's how they worked the repos. Maybe I'll give it another try someday.
(edited my previous post to sound a little friendlier, sorry!)
Ubuntu is that good, that if you get (so many) crashes, you should think of hardware that is faulty. Someone mentioned a failing power supply, you might also check the memory (RAM), you can use the LiveCD for that.
You can also check whether your hard disk is still OK, using the Disk Utility, and see what S.M.A.R.T. has to say.
Even the new 12.10 already runs quite well on the computer on which I have it installed. STOTA (State of the art), but very stable.
You should think of hardware.
Are you overclocking your system?
For info on UEFI boot install & repair - Updated Mar 2015:
Please use Thread Tools above first post to close thread when/if answered completely.
I did the hardware test. S.M.A.R.T over all assessment test shows DISK is OK and didn't had any issues at all in 12.04. It only started after upgrading to 12.10. Anyways, I have done some repairs and reinstallation of packages and for now it is running and if nothing happens till Friday than its good otherwise I am going to make a fresh install for 12.10. Thanks everyone and will post further on upcoming Friday