SOHO Network Problem – shares not visibl

3 networked PCs, one with Windows 95, one with Windows 98, one with Windows XP; also one shared printer.
A problem developed where the XP computer could access and display the entire network, while the other 2 would not display the contents of Network Neighborhood nor display the entire network using Windows Explorer. However, any PC could print on the one shared printer.
Next problem: the situation flip-flopped — the 2 older PCs with Win95 & Win98 could “see” each other on the network, while the WinXP PC “fell off” the network.
Another factor that may/may not have influence: Previously, the networked PCs had the opaserv worm which has been removed — might that infection still be wreaking havoc?