Hello Olga,
thanks for the fast and helping answer. I made sure, the directory does exist (and is accessible) and it works fine now.
Currently I use the newest (non-beta)-version 3.6.1309.
The reason of this behaviour was, that I use junction-links and the junction-link of c:\Users\<user>\Pictures was linked to a no-more-existing directory. So VideoSplitter perhaps tried to create it and its subdirs and did not succeed. So the directory couldn't not be opened for showing. Repairing this, and this works fine...
So, if you want, you could implement a little message-box displaying, that the snapshot could not be created, if you want.
Thanks a lot,
Michael
BTW: Because of the lossless-editing your video-splitter is the most used video program I currently use.