I've seen similar discussions, but, no solution.
I can't create a slideshow i LrC. I use just 4 pictures with a size of approx 25MB each. It takes about 10 minutes to complete the task when selecting 'preview'. An error message is displayed when selecting 'Play'. After the message is 'Preview', 'Play' or 'Export Video' not selectable. Export PDF is, and a PDF is created with my pictures and settings. No MP4 is created when selecting 'Export Video instead of selecting 'Play' as above. Select no 2 of 'Export Video' with the same file name gives the answer 'Task in use' or similar and a progressbar is presented i the upper left of the screen. I have restarted LrC with the same lrcat, re-installed LrC and pointed on my lrcat, and a clean lrcat and new and one of my older backup files. The same result for all trials. I use an updated Win10 Home computer, LrC 12.1. Both in Swedish version.
To create a slideshow with the same 4 pictures work fine on my laptop with Win11 Home and LrC 12.1. A preview takes about 10 seconds. 'Play' and 'Export Video' works also as it should.
Any suggestions to repair my Win10 main computer.
Best Regards //Kent