Borderlands LAN Issue

Basically the problem I am having is this:

Whenever I host a game over LAN, my brother can see and join it, no issues.
Whenever he hosts a game, I can see it perfectly fine. When I try and join though, it timeouts on me. 30 seconds and then timeout.

I think it's a Vista-XP issue, but not sure.

I am running Vista 32bit.
He is running XP Pro 32bit.

Using a Linksys (T-Mobile @home) router. I opened all available ports. Made sure that none of the ports are being blocked locally on my PC or my brothers. Antivirus is not the issue, made sure to enable game pass through for Borderlands and the ports.

I use Kaspersky, and I think he uses AVG (Unsure).

I disabled IPv6, along with Topology and the Responder (Think that's what they're called).

Made sure my wireless was top of the list for connection priority.

Also, we could connect easily to each other previously. Both ways. However, I contracted a virus, which I got rid of by way of Kaspersky and System Restore. After the restore, I cannot connect to his server anymore.

Please help!