This has been ongoing for the last month or so.

It has been a bit intermittent but is now permanent.

I can't see any of my windows computers, my imac pops up in finder occasionally but I can't connect, it just times out then disappears, my xbox can't see the mbp via connect360 either. If I try to connect to my imac by using Go>Connect to server I get the following error - There was a problem connecting to the server "computer name"

The imac on the otherhand can see all the computers except the MBP, my xbox can see the imac, as can aceplayer on the ipad.

So I presume it is a problem with the MBP, I had little snitch enabled but have since disabled this and still have the problem.

Any help/suggestions?

It is a early 2011, running lion.