Right click on Windows button in bottom left and choose Command Prompt (Admin)
type this in
sfc /SCANNOW
return
then when it's done type
DISM /Online /Cleanup-Image /RestoreHealth
return
May or may not help, but it's something to try. If your Launchbox in on a different hdd than C then type cd E: or F: or whatever the drive letter is before doing these.
If that doesn't help I would install a fresh Launchbox from Launchbox.com in a new location, then copy your data, themes, LBthemes folders and if you use music copy that folder same for videos from the current one to the new one so that you don't lose anything and see if that helps. In this case you're starting fresh yet keeping your data at the same time.