I have been running QT on Windows 10 since I installed Win10 with no issues. I got up this morning and it would not open any files, kept giving error 1856. Did some searching and found that now I have to run as Administrator. Anybody else run into this? Is this part of a recent Win 10 update I wonder?
If you suspect the problem is related to an update in Windows I would suggest you take a current backup and then restore to a time before the problem occurred. On a quick machine the whole process should take around 15 minutes max.
If this clears the problem you then will need to look carefully at the updates that Win 10 next installs.
A good backup image taken when the machine is clean & stable is a good insurance to have.
Sometimes I get those incidents with Microsoft Security Essentials picking up on
something bad that happens to that application and it then prevents that application from opening. I then have to use the restore function in the tools to get back to normal. In my case a warning pops up that I do not have permission to open this application.
If your AV is interfering with Vegas then simply set your AV to exclude those program folders Eg set C:\program files\Sony and c:\programData\Sony as folders. not to be swept by the AV. Very easy to set up in Microsoft Security Essentials and Defender. Personally I would also exclude my media folders. In my case D:\Sony Media. Your folder name will differ.
Well worth a try although I have never experienced problems with AV. Certainly GrassValley recommend exclusions with the Eduis NLE so it may be effective with Vegas.