>>Couple of thoughts - is the laptop part of the domain, and is it connected to your domain when you're doing this? Kinda sounds like sometimes it's part of the domain and others it's not???? Of course that doesn't explain whey the ping returns your servers address ...
>
>There is no domain at home. I only have two computers, the PC and the laptop.

Hmmm...that is really strange. Maybe it's part of a workgroup or something?? Perhaps it something with your router causing that?? I'm at a loss as to what it could be.