seeing computer on the network

I have two machines on a network, a desktop and a laptop that is running wireless. the laptop is able to print and connect to the net but is unable to access the desktop machine. I am running XP home on both. All of the files have sharing. The desktop cnd see and go into the laptop. the laptop can see the desktop through the view network computers but when you try to access it you do not have access. I have looked at everything possible that would be locking the desktop out but to no avail. The only thing I can think of is I installed System Mechanic 6 and somewhere in their program it is blocking access. Any thoughts would be greatly appreciated.