Win XP cannot connect to the network

A client added a new Windows XP Professional SP1 machine to her workgroup (with existing Windows 98SE and Windows Me).

Somehow the XP has trouble accessing other computers. It can ping, tracert or pathping the other two in DOS prompt. But once it tries to access the other two computers and the printers attached to them using Windows Explorer or My Network Places, the other two computers become inaccessable.

All 3 computers were installed with TCP/IP protocals. I manually configure a fix IP address for each one (192.168.1.xxx) in order to eliminate the possiblity of different subnet. Hub and cable are tested OK.

Can someone please help.

Thanks.