hard disk threashing/ system halt

Hello everyone, this is my first time in a forum, so i hope this will be a good experience and that i follow the correct Etiquette.

my problem is that i am running XP Pro with latest service packs and updates as of last night. The system is a P4 on and ASUS p4p800, with 1 G RAM and 250 HDD with 5700 Graphics card. Applications are Office 2003 with latest updates, Dream-weaver etc.

I have noticed that the system stops completely randomly whilst the hard disk thrashes away and the CPU goes to 100%. As said it is random and i can be using any application when this happens, although it does happen more when Office is being used.

I have re-installed office, and i have even completely re-installed everything including OS. But it is still there.

I have looked in the Event logs for any help, but nothing is logged. The system after a few seconds goes back to working Okay and at some other random time will happen again.

Does anyone know what this could be? and is there any free monitoring software that i can install to try and isolate the problem. I feel that it most be hardware orientated but i have changed the 3200 memory and CPU but still happens. Temperatures of the system are okay.

please help!

How do i get to know when their is an update, does this system email me? or is it a lo-gin and check. Thanks for your help folks!

Could be a virus. Update your antivirus tool and run a full scan.

forgot to mension that the system has been checked by two virus checkers Nov 8 with latest definitions, and shows nothing

Reboot into safe mode...if it goes away, problem is most likely software related (i.e., virus...spyware....driver conflict...etc). If it continues, definetly hardware issue. Please try this and post back.