Install Problems with Vista, cannot log in after signing up. (greeeeat title)

hey!
I downloaded and installed wuala on my lapotp with Windows Vista. (It was already installed ... so dont blame me and surprisingly it does work quite fine)

I typed in the invitation code and already had some problems setting up an account (wuala crashed while sending the stuff). It worked when I turned off Avira AntiVir (windows firewall is also working and was on during signing on). When I try to sign it says Username not found (or somtehing similar... its the german version ;)). It doesn't work neither with the firewalls turned off nor turned on.

Ya ... well great. What's the problem here?

Wuala also says that it cannot find usernames which appear to exist. (When I tried do sign up, the first username I tried was said to be already in use. So I typed this one in later, just to see if it tells me I've got the wrong password. Surprisingly it says username doesn't exist)

Looking forward for your answers!