Not sure if posting this in the right place or not, but here goes...

My computer has recently started crashing when left idle for periods of
0.5 hour or longer. It reverts to a DOS screen that is labeled Novell
NetWare Ready Firmware V1.00 (940809)
Boot failure and instructs me to insert a boot diskette in A.
The full message is as follows:

Novell Netware Ready Firmware v1.00 (940809)
© Copyright 1991 – 1994 Novell, Inc. All Rights Reserved.
Sis 900/7016 PCI Adapters DOS ODI Driver v1.10(001228)
© Copyright 1998 SiS Corp. All Rights Reserved.

RPL-ROM-ADR: 0007 952B 5115

RPL-ROM-FFC: 5 Not Found

Insert BOOT diskette in A:
Press and key when ready_

To restart the PC, I must turn the main power switch off then back on and
the PC will boot up fine. Then the same thing happens again when left

I am using Windows XP Professional

TIA for any assistance or suggestions