Hi Axel,
With ATI driver 11.2 I am seeing an issue where FPV is not redrawing the whole screen while viewing pictures; zooming, landscape to portrait, last tested version where redraw is working properly 11.1, rolling back to 11.1 resolves issue as does disabling GPU acceleration. I've included a screen capture below to illustrate the problem. Let me know if you would like any further information.
Screen capture: http://dl.dropbox.com/u/7582065/2011-02-27_103048.png
Windows 7 x64 SP1
Intel I7 920
ATI Radeon 5870
FastPictureViewer Professional 1.4 (Feb 26, 2011) Registered