There are a number of things that could cause this. Bad memory is right at the top of my list. But try starting in safe mode to see if it's a bad driver or other software issue. To do this, start tapping the F8 key as soon as your computer starts up. Keep tapping it until you get a black safe mode menu screen and choose "start in safemode". If you can reliably boot this way, then it is a software problem if not, it can still be a software or hardware problem.

Yeah bentkey is probably right with the memory thing. open up your machine and take out the memory and put it back in. If it still doesn't work then one of your memory sticks is bad and needs to be replaced. if you have a warranty you can call up and get some new ones for free. Only do this if you cant boot into safe mode.

If all else fails and you have no other options then the power supply might not have enough power in it to give to your machine. If this is what is happening your computer will slowly die (it happened to me and after at first the computer would just shut off after an hour or so, then thirty minutes, then it would just boot and shut off). Your computer manufacture will probably give you a new computer dell gave one to me (it was even better then my first everything was upgraded).

So consider those things but like i said if you can boot into safe mode then you dont need to try any of those things

Sarah, has your PC always done this, or did it run fine until recently?

Can you remember making any changes shortly before this started happening, eg installing new hardware or software?

Not really no...however, I just moved my computer and switched from DSL to Cable, and it doesn't seem to be doing that weird reboot thing. Maybe the DSL was doing something weird to my computer?

That would be highly unlikely.

This is maorly caused when some device driver does not match or not properly configured.

you should update your drivers if you use any new hardware, and possibly there is chance with your memory also going bad. check it.

Saran