Win7 Pro sees less than Starter and Home

I have reset firewall settings to default on all three computers. Win7 Pro only sees other Win7 PCs and not a router-shared drive nor the XP, and yet the Win7 Starter and Win7 Home both do. All have same workgroup name.

Any suggestions on how to remedy this would be greatly appreciated.

Thank you,
Rick Dettwyler

I'd first temporarily disable all firewalls to ascertain if the problem lies with one of them or elsewhere.

check your homegroup settings, some of the settings can HIDE and not show, id check thne