WIN2000 PRO STOP ERROR

I have a user getting these error messages. At first she said they seemed to occur mostly in excel – which she uses frequently. But now happens more frequently sometimes when printing.

Driver IRQL_Not_Less_or_Equal
***Stop 0x0000000A (0x57Fb0c24, 0x00000002, 0x00000000, 0x80062Ede)

Driver IRQL_Not_Less_or_Equal
***Stop 0x000000D1 (0x00000001, 0x00000002, 0x000001, 0xEB81F199)

AMD 1300, 512 MB, 30 gig Hd, Win2000 pro, McAfee Virus Scan