Strange problem when creating disk...

[z]

VideoStudio 10+ SP1
The source video is 25fps encoded by AlparySoft Lossless Codec (from DV cam)
When I watch source video in the "Edit" screen frame-by-frame all is ok, but when I try to "Create disk":

Code: Select all

MPEG files
24 bits, 720 x 576, 25 fps
Frame-based
(DVD-PAL),  4:3
Video data rate: Variable (Max.  8000 kbps) 
Audio data rate: 256 kbps
Dolby Digital Audio, 48 KHz, 2/0(L,R)

in the "Create disk" preview I can see that every fifth frame is the copy of fourth frame, i.e. every fourth frame duplicates. This is excatly on the DVD disk after creation although all is ok in the "Edit" screen.

What it can be? I know that this happens when converting PAL-NTSC, but no converting here