Well ..you can start by disabling the "simple file sharing" option...this solves some share problems that I know off...

You find it in Tools -> Folder Options -> View ->scroll down and deactivate the option "Use simple file sharing (Recommended)"

Check to see if all computers have TCP/IP instead of NETBEUI or something (obvious but sometimes overlooked)

Check this link for more tips on troubleshooting these pesky Windows XP Home problems

Yell if there are any other problems

C.