.509 system freezes

On certain apps, allowing the firewall alert causes the entire system to freeze, i can move the mouse for about 5 seconds before that freezes too.

It so far has only happend with 2 programs, xfire (after first instaling cis) and company of heroes (The first popup i got for it was fine, but i think the 4th time i ran the game, then quit, i got a second pop up for it which caused it to hang.

Temp workaround is to add the program to trusted apps before the alert has a chance to appear.

Vista x64 sp1
Using default settings

Have you tried setting the firewall and D+ to Training mode? Run your programs (say 10 minutes), then exit the programs and reset the firewall and D+ back to the mode they were previously.
Rerun your programs, they should function properly without any freezes.