Have you updated the video driver?....Did you reinstall the OS at any point?...or are you dual booting xp and vista?...

Hit f12 at boot up and run dell diagnostics and see if anything is wrong with the video card.

I did all the tests, all passed successfully.

i dont know what's going wrong with this laptop. vista can't load at all now, XP works well for 10 to 15 mins then the screen color turns all blue , gree or red then locksup...

Problem Solved !

the only change i did to this computer lately was to upgrade the bios to A09, so all the problems happened since then.

I flashed the bios back to A06 and left the computer on for 9 hours now doing disk defragmentation, it didn't crash until now.

Anyways, here's what windows Vista reported about the problem.

windows XP event log wasnt able to log anything about the crash.

Dell Diagnostics utility wasn't able to report any problems too.

DELL PLEASE CHECK YOUR DRIVERS BEFORE POSTING THEM TO PUBLIC !

Problems started to appear again :( , i don't know what's going wrong with this 8400M GS ...

and ithink it's a common problem, others on the web has posted same symptoms

here

http://www.notebookforums.com/thread207967.html

and here

http://forums.nvidia.com/index.php?showtopic=51835

i found this post only, that has a possible solution to the problem:

http://forums.nvidia.com/lofiversion/index.php?t30573.html

I've had the same issue appearing suddenly on a Dell M1330 with a NVidia GeForce 8400M GS, after 5 months of use : The computer would freeze randomly (usually after some minutes, depending on the applications open), then the screen turned black, and vertical lines would started appearing, progressively filling the screen with white. It often happened also when rebooting the machine afterwards, and sometimes even the BIOS screen would appear wrong (e.g. some blue patterns instead of the usual black background).

THIS IS MOST LIKELY *NOT* A DRIVER PROBLEM, BUT A HARDWARE PROBLEM INSTEAD.
(the messages from people having reinstalled windows or changed drivers without success should confirm this if there is any doubt left).

I've called the Dell support, and we came to the conclusion that it was NOT a driver problem, since I've had issues when running on the VGA driver too (although without freezing the machine), and the BIOS screen corruption also indicated that windows wasn't in cause.

So they started by replacing the motherboard, since it has the gfx card embedded in it. Unfortunately, this didn't change a thing, so the gfx card was out of cause too. Next thing, we changed the RAM modules and the heatsink, and there bingo ! No more freezes and weird screens after that. I couldn't say for sure which one was the culprit, it could be the memory that took a hit (that's rather common after all) or the heatsink that didn't work as good anymore, or even a combination of the two.

Anyway, since I haven't found any information myself about this problem when I was googling for it, I thought this could be useful to others. First start by checking your gfx card and the heatsink, it's possibly just a overheating problem. If you have shared memory, try changing the RAM modules if you have any at hand. Finally, if your computer is still under warranty, make sure to get the support to replace the gfx card or the RAM if you have any reasonable doubt they're in cause (and if you have a good support...).

Hope this helps, good luck !

nb1: Oddly enough, I did run all the diagnostics tools provided by Dell, including a 2-hour full memory test that passed. So no matter what the tests tell you, they're not 100% reliable.
nb2: one tips: if you need to use your machine while waiting for the support to replace the hardware, try switching to the standard VGA driver or run in failsafe mode. This way the graphics engine is greatly limited (no more Aero, less memory, etc.) but then it puts less strain on the machine and makes it rather stable. That's how I've done while waiting for the replacement pieces, as it's my work laptop. I did see some strange patterns on the screen occasionally, but no system freeze at least.

==================================================================

any answers? im i the only one in here who experience this problem?

Just FYI I'd use Memtest.org's program overnight to find memory problems.  Easier for you and cheaper for Dell than having to replace motherboards and things :)

Glad the cause was tracked down though!