dLAN problem :X

Well, today a friend called me asked me if i could fix his dlan (the ethernet which goes trough the electric leads in your house).
It was always losing connection and fkin slow.
After a few mins i fixed the losing connection thingy by forcing ips for the computers (the other one is connected with simple LAN and is working fine).

After that everything was working fine except that it was fkin slow in uploading/sending requests.

He suggested to install the software delivered with the dLAN devices (which wasnt installed before)
That was the beggining of the end!
After I did that, nothing was working anymore, not the connection from the computer to the Fritz.box (router) and no connection to the internet anymore.
I tried everything (asigning IPs, not asigning IPs, forcing IPs in the router options,...) I wasnt even able to get an internal connection (computer<->Router)

So now my question:
How can I fix that?

randomchick