Windows Live Messenger doesn't work

I've tried every trick I know to make it work. I've tried updating the router firmware, tried a few fixes that I found here on the forums that work for other people, and even tried updating the Live Messenger...No go...

The problem is that my messenger gets online, but as soon as it does, it disconnects the entire network...I don't know if it's conflicting with the router...But if it is, can anyone tell me what ports I should open up for it to work?

Oh and I haven't tried to connect the PC directly into the router because my ISP is a pain in the neck to connect to different MAC adresses since you have to call them and register each time you switch.

Well anyways, can anyone give me a solution, maybe you've had a similar problem after you installed Windows 7?

I think it's easier for you to guide me through where that device manager is because my Windows is in Portuguese since it's Brazil's version...But I'm sure that's not the problem since they're all the same, just different languages...Anyways you think you could tell me where it's located?

What happens if you disable your routers firewall?

Well...I'd rather not disable my router's firewall...But I'll try it to see if it's the culprit. Oh and I found the manager but it didn't show any updates except a few optional ones.

I put the PC on DMZ, unfortunatelly it didn't work. I'm just hoping someone had the exact same problem I have.

Tried unblocking the ports. Needless to say, it didn'r work. I'm just wondering what has gone wrong. Maybe I should reinstall Windows 7.