Sorry man. With my luck, when I take my laptop to work and then bring it back home it won't work for me either. BTW, I activated both Guest accounts but I don't know if that had anything to do with it.
Solved!!! This is very embarassing. Man o man, I feel like a complete dufus. Finally called up my friend and the first thing he told me to do was turn off my firewall (which is ZoneAlarm) and that cleared everything up. Then all I had to do was add my son's IP address to my "Trusted Zone" and that was it. I had no idea ZoneAlarm would block my access to another PC; I thought it would only block others from mine. Now I can set up firewall and anti-virus programs on my son's computer and the case is closed. Happy New Year!
Here's another question. When sharing printers, do the printer drivers need to be installed on each computer or only the one that the printer is connected to?