Xp Rejecting Access

I have an XP Home machine running as a file server on a network. Its sole function is to store files/documents.
Users on the Network access files on this machine, edit and save them to this machine.

Problem: I have a windows 98 machine that is unable to access this machine at different times.
Have tried rebooting, checked shares etc. the other Win98 machines can access it Ok, although one or two have also done this.

the Win98 machine in question can see the network and can access the other machines as well as another XP machine on the network

Any suggestions?

Thanks!!!!