Network Connections Problems

[HungLikeJesus]

Every few minutes I get a pop-up window (as shown below) asking me to choose a network connection. Sometimes this pops up once in an hour, and sometimes every few seconds. When it does, any pages loading in the browser (SeaMonkey 1.1.8) freeze as if there is no network connection. I hit "close" and the browser is back to normal.

Does anyone have suggestions as to what is happening? It doesn't seem to matter if I'm connected through our office LAN, or through a public WI-FI or through home dial-up. This has been going on since last August when I got this computer. I don't remember if it happened with my previous desktop.

I also don't know if it happens with IE, because I don't use IE very often.

This seems minor, but it's a little frustrating.

Thanks.