Aye, as the Seeker said IRQL_NOT_LESS_OR_EQUAL_THAN is almost always a driver problem, as I found in numerous past experiences.

I see that you both have NICs from linksys. Perhaps there is an issue with that manufacturers drivers? If possible, try to obtain a different NIC (I"ve had good experiences with most 3Com and Intel) and see if it makes any difference.

-3vi1