Network Password Problem

Please help! I have two PCs connected via a Cat5 crossover cable. Both machines are running Win 98 and their Ethernet cards are installed and working correctly (according to the Device Manager). Both machines appear in the Network Neighborhood and are correctly named, appear on the correct workgroup etc. However, if I try to look at the contents of C: of “machine 1” from “machine 2”, or vice versa, I’m asked to supply a network password. I have no idea what this password is or even why Windows is asking for it – no passwords are in force for print and file share. Any thoughts??