*.mov Videos on QuadCore PC play Sound but show no Video

[lockkopf]

I use(d) XnView versions 1.95 up to 1.92.2 installed on 3 computers and
everything is working fine except for one combination (in all XnView versions):
*.mov-Videos on Quad-Core-PC and XnView-Browser is or was started first
In this case in Preview, View and Fullscreen the sound is played but no Video is shown.

*.avi-Videos are always working, *.mov-Videos on non Quad-Core-PCs are always working

Only if I start by Send To or in the pure Base-Mode *.mov-Videos will be shown,
if I then open the Browser by Ctrl B this *.mov-Video will mostly still be shown,
if using the Browser-button this will work only if I first use page up/down keys several times,
if I then navigate in the Browser all selected *.mov-Videos will mostly be shown.

This happens with: AMD Phenom Quad-Core 4 x 2.3GHz, 3072 MB RAM, Graphics Nvidia GeForce 8400GS 256 MB
On all other computers having no Quad-Core 4 it's working fine.