Question : Problem: Inspiron 600m lockup on LCD use

Hi all.  Been a while since i used EE, and getting used to the new layout.  But, on to the question.  My friend has a Dell Inspiron 600m Laptop.  He was complaining about the laptop randomly displaying strange characters then rebooting.  My first guess was overheating.  So, he brought it over and we took the keyboard off, and i cleaned out the innards with a can of air.  Everything seems fine for a few days, but it started up again.  He has it plugged in to the SVideo on his TV and usually doesnt use the LCD screen.  Everything works fine in that setup.  When he opens the LCD screen, it does the screwed up screen and then reboots.  I only have a few possible solutions.  Video memory is failing, somehow the LCD Screen is shot, or Windows is all jacked up.

UPDATE:
He said it only happens when Both the TV and LCD are in use.  If the TV or the LCD are used by them selves, it seems to be fine.  Possible video memory?  The extra desktop would be using more memory.  Possbily a chunk of ram that is bad?

Here is a rough summary of the above paragraph.

PC Specs:
Dell Inspiron 600m
he has 768mb of ram (256 and 512)
Windows XP Professional

Problem:
Reboots randomly when LCD is used instead of external S-Video to TV.

Solutions already tried:
Driver reinstall
Good cleaning with a can of air.

Any other ideas?

Answer : Problem: Inspiron 600m lockup on LCD use

I would be tempted to reinstall the OS and software from scratch.  Then do some testing over a few days to see if the problem starts happening again.  Prior to doing any work on it I would create a image of the system so all could be put back as it is prior to any work being done on the system.