Mapping Shares

I have an XP Pro PC that fails to connect the mapped
shared drives (a Windows 2000 PC serving as a server).
They appear with the red X thru them. After clicking on
them they are OK and stay connected fine, other than the
display of files is much slower that the Win 98 PCs that
map the same shares. Running TCPIP (have also tried
Netbeui with no change) Any suggestions?
Also have one PC that when the user goes to Shutdown it
always shows standby as the default. When he changes it
to shutdown it jumps right back to standby. He ends up
just powering down with the switch