12.04 become unusable

[G.]

I have 12.04 installed on a Samsung NC110 with 2 gigs of ram.  12.04
constantly stalls and crashes to the point where I can not use it.  I
have tried Unity 2d to no avail.  It worked fine when I first
installed it.  I had the same experience with 11.10.  11.04 was fine.

I have switched to Lubuntu 12.04 which works fine with the exception
of a jumpy touch pad that causes the cursor to land at various points
on the screen when typing, a problem not found in 12.04 for me.  My
other complaints about Lubuntu are minor, such as the lack of a gui to
control screen brightness.

Any suggestions on how to determine the cause of the problem(s)?