Empty video after unlocking workstation
 

I updated a few days ago Winamp from 5.5 to 5.572 and installed also the newest ffdshow 1.1.3452 (24-05-2010).
Everything works fine but when I lock my computer with Winamp still running but no video running, then unlock it and start a video in Winamp, I have sound but no video. The video window is transparent. This happens to any kind of video (avi, mpg, wmv etc.).
After re-starting Winamp everything works fine again... :)

My system:
WinXP Pro + SP3
AMD 5600+
OnBoard graphic
4 GB RAM