P2P Networking

I have a P2P network at home with a multi-boot Win 98-Win 2k machine and a Win XP Home machine. The XP machine can access the Multi-boot machine no problem (when the permissions are set), but the Multi-boot gets the message “User has not been granted the requested logon type at this computer”. Both machines can see each other and can, of course get answers on pinging. I have tried setting myself an acccount on the XP machine as various types of users, but all to no avail. The multi-boot machine has no problem accessing any other machines around the house (Win 98 or Win 2k), only the XP machine gives me an error. Can anyone give me a hint?