Skype causes 100% CPU load

[guardian_de]

I'm running VB 1.4.0 on Ubuntu 7.04. The guest OS is Windows XP SP2. I installed drivers for the Logitech QuickCam Communicate STX and Skype. USB support and guest additions are configured too. Other than that it is a fresh install.

When the Skype service is started - i.e. no audio or video call active, just idling - VB occupies one of my two cores. When I quit Skype the load goes down to a normal level.

Any ideas about what's going on here?