Cant connect

I have a friend how cant connect to our forum, but everyone else can. I remember some time back a lot of people had this same problem, it didnt help clearing your cache and all that, but someone posted a link (from a french side I think), where there was a solution to this problem. Just by downloading a program and run it on your computer. Restart and your where good to go again.

Does anybody have that link or another way to fix the problem.