Theres something eating up all my ram on my comp. At any time no less than 80% of it is being used (usually around 95%) even after I shut down every program I can find running. When I open the task manager in Win 2k advanced server and click on processes I see the main culprits are "System Idle Process", "Issas,exe", "rtvscan.exe", "NISSERV.exe", and "svchost.exe". I can't end any of these processes so could anybody tell me what these processes do and why they're using so much memory and how (if possible I can stop them).
I've got 128mb of SDRAM if it makes a difference.

Also the strangest thing is I'm having the same problems when I run win 98 and RH Linux 7.3 on the same machine. If I try to run any program under any of the OS's it either runs very very slowly or crashes the whole system.

Any help is much appreciated.