I've networked an old 98v2 PC to a Win2K PC, but it don't quite work right...

The Win2K PC can see the Win98 one fine, although sometimes it says it doesn't exist at all and we have to reboot one or both PCs. When it can see it though, it works perfectly for viewing files.

On the other hand, the Win98 PC claims it can see the win2K one, but when I try and view anything (either through Network neighbourhood or tring to explore "\\Win2KPc\SomeSharedFolder" I get a password popup. The machine has a clean install of Win2K so I know there is only one password I used, but this is not accepted. How can I make it stop asking for a password?

On a related note to the first point, we have a modem in in win98 PC which is shared over the network. Sometimes this works, but often the Win2K PC just refuses to see the internet connection - maybe related to the network connection being flaky?