2 desktop connected and sharing, 1 laptop connect but not sharing

Help! I have 2 Dell Desktop Computers running WinXP and they are connected
through a wireless network... The wireless network is running between the two
of them fine(file sharing, printing, etc all works) however the laptop can
print, get onto the internet, but it wont share files.... Everything has been
checked and double checked over and over... I have been trying to figure this
out for almost a week and every suggestion isnt working... any ideas?

Thanks