Dell Optiplex reboots, help!

[Gizmokid2005]

The Chassis Intrusion Detected is a stupid sensor that some PC cases have on it that if the case is opened the computer will shut off. It is something that you can turn off in most BIOS' options.

[n2ho]

The Chassis Intrusion Detected is a stupid sensor that some PC cases have on it that if the case is opened the computer will shut off. It is something that you can turn off in most BIOS' options.

I disabled Chassis Intrusion Detected feature in the BIOS. Temperature of the processor seems to me OK (checked by touching the heat sink), cooling fan works OK. Lets see what happen next.

[n2ho]

Today I tried to make a backup of my data files on DVD-RW, and couldn't do this because damn computer every time rebooted in the middle of DVD burning. After 3 times I gave up. What causing this?

[TurcoLoco]

Today I tried to make a backup of my data files on DVD-RW, and couldn't do this because damn computer every time rebooted in the middle of DVD burning. After 3 times I gave up. What causing this?

I agree with Cauz, this does smell like a hw issue which would commonly require replacing or repairing!

Usually happens one - twice a day, very annoying, you can lose good chunk of work if you are writing or doing something.
Contacted Dell, they advised first to go to msconfig and disable all non-microsoft services, but it didn't help. Then they advised to backup all data and reinstall Windows, which I don't want to do unless no other choice. Any help/ideas??

This is quite typical of vendors and their lousy support dept. These are new laptops and presumably still under warranty? As Cauzomb said, contact Dell for replacement. You should not have to stop and services/programs that came with the laptop in order to prevent the rebooting. What they suggested sounded like a troubleshooting suggestion but even if it worked, it would not be a good workaround or a fix.
Random reboots are generally a sign of bad PSU or CPU (even if not overheating).
I'd also seen similar patterns on a few IBM laptops where mobo had to be replaced...
Don't waste any time if these laptops are still under any kind of warranty!