Vista - Repost: Problem with videocall

I need to repost this, because i did not find any solution:

I just assembled a brand new PC and installed vista home premium 32.
I have a very annoying problem with videocalls.
Turn on the PC, start messenger, open a chat dialog, click on the videocall
button.
As soon as the other contact answer the call, messenger freeze.
After a couple of minutes I get the message:
"Messenger cannot connect you to "contact name". Please try again later"
and the program is unfrozen.
I just recall the same contact and everything works fine.
Webcam is MS VX5000 and it work fine with Y!Messenger and Skype as well as
stand alone.
I've tried everything: firewall on/off AV on/off, cable connection vs
wifi connection.
reinstalled messenger two times. Nothing strange on windows logs. No idea
how to read messenger's logs tho.
Now i'm puzzled and out of ideas.
Help please....

ps: The other PC running XP is fine.