FreeOTFE Explorer doesn´t work on XP?

Hy:
Perhaps someone could help me:
I use FreeOTFEExplorer as portable version 3.51 on a USB-Stick FAT32
formatted.
On my W2K system everything is running normal;

If I try the same thing at my XP SP2 machine, the FreeOTFE Explorer
launcher for PortableApps.com takes 99% of CPU-Time, GUI will not appear.
same thing if i run it with administrator-account or normal user.

What could it be?
axel333