Help! Computer is being freaky

For the past week or so, my desktop computer's internet connection has been wonky. Only my desktop computer. When I use my laptop's wireless connection, everything is fine.

I keep getting Connection Interrupted errors, and/or pages are loading funny.





I tried checking the firewall settings and matched the desktop to the laptop's settings (Medium).

The only new thing on my desktop is that I added the AVG Safe Search Add-on to Firefox. I disabled it tonight, but am still getting the error message.

I tried unplugging the router power source; that did nothing. I disconnected the cable from the computer to the router; that didn't help. I'm getting very frustrated here.

I suppose I can try uninstalling the AVG tool completely and see if that makes a difference.

Does anyone have any other ideas?