Help.

I have recently wiped my laptop Inspiron 2650 clean and started afresh as I seemed to have picked up some didgy viruses.  I re-formatted the disc and loaded Windows XP Professional with Service Pack 2.  Also updated the bios and chipset drivers and loaded Adware, Spyware, a firewall and AVG virus checker.

My computer now seems to freeze or crash if I leave it on for any length of time but don't use it.  Also, if I put it into standby it wont come out again.

Any hints or tips.  A friend of mine thought that maybe it's a hardware problem and that my computer is simply overheating.  The fan does seem to run a lot.