My old Sony Vegas 14 pro worked fine. While updating to Windows 10 I got Sony Vegas 18 pro - for some stupid reason. Sometime during this summer I found myself for a while adding a deleting a dll file from the programs plug-ins-folder, to be able to work with MTS files and on the other hand some HQ - MP4 files. One file worked when deleting the dll. -file and the other worked when keeping it. Frustrating - but It Worked! Obs! File is compoundplug.dll. AND NOW, Sony Vegas wont play my HQ MP4-files at ALL. Now from what I understand Sony Vegas has stopped being compatible with certain high resoluted MP4 files. Anyone got an idea how to get it to work, or do I have to give up on Sony Vegas?? Alot of money spent so far and I like the program. User since 2010. Thanks!