Cannot Boot Win2K into Safe Mode

[hwfa]

I'm running Win2KPro with all critical updates as of 15 Feb '05.

I can boot the system normally as administrator or as non-admin.

I cannot boot into Safe Mode. I get Stop Error 0x0000000A IRQL_NOT_LESS_OR_EQUAL. Then there's a bunch of text telling me what to do including "boot into Safe Mode".

Apart from Windows Updates I haven't installed anything new recently. I may have acquired the Tannick.B trojan but I believe I have deleted it (with the aid of Norton AV 2005)

Any and all ideas much appreciated ...