Sorry, a bit OT, but still in "video authoring..."

I'm trying to use Power video karaoke v. 1.2.13 to author a video karaoke in
avi or mpg format.

Everything's fine with the program until I create the video:

if I use the included bckgrnd.avi in the "example" directory, (1 sec loop
avi, gspot says:
C:\Programmi\Power Video Karaoke\Examples\bkgnd.avi ^ 135 KB (or 138,240
bytes) ^ AVI ^ DX50/DIB ^ 640x480 (1.33:1) [=4:3] ^ 723 kb/s ^
00:00:02 (30 fr)
then it's ok.

If I use clock.avi in c:\windows dir (gspot says:
C:\Documents and Settings\Guido\Desktop\karoke\clock.avi ^ 81.0 KB (or
82,944 bytes) ^ AVI ^ RLE (_RL8) ^ 321x321 (1.00:1) [=1:1] ^ 44 kb/s ^
00:00:12 (12 fr) ^
it's also ok.

BUT any other avi i try to use, compressed, uncompressed, long, short... OR
even any jpg/bmp/png image (which the prog is supposed to support) doesn't
work...

Any idea on what I can do, e.g. how I can convert my pics or avis to use
them in the video karaoke?

Thanks,
Pippo