hmm ok,
did you check your eventlogs if something is showing up there (i dont think so, but you never know...)
on the other hand, does it only freeze if you use the modsets button?
why do you need to add the whole repository? is it crashing if you only select the modsets?
what happens if you just select the "[3cb] public server - [3cb] public modset" from the dropdown in the bottom?
it should add the according modset to your addon groups list...
(i never use the modsets button, if i need a diffrent modset [that isnt connected to a server] i usually change the modset for the server in the online tab and than select it via the join server dropdown)
does it work for other repositories?
(try to add
ftp://66.85.14.170/.a3s/autoconfig and check if its the same behavior)
i cant remember, isnt there something like a debug option under tools or help?
if there is on, pls try it...
btw. what is the name of your windows account? any fancy characters or something?