Some time ago I created custom sheet format and it seemed to become corrupt but I can't remove it from the list in solidworks, furthermore every time I accidently press the format an error message pops up and its duplicated in the list with "~$" before, the duplicate also being corrupt. Has anyone encountered this before or knows a fix?
Have you tried copying your good files to a new folder, then pointing to this new folder at Tools > Options > File Locations > sheet formats? If that works you could try to go back and delete the entire folder that the old bad files are in.