You didn’t happen to check in the “Intermediate” or “Saved” folders did you? If you did be sure to take remove them from the depot. Also none of the visual studio related files should be checked in either. (.sln, .sdf, etc)
Also, sometimes files that aren’t even in the depot can sometimes be made read only, so that could be it too, if thats the case you could manually untick the read only option for any files that aren’t under source control. This should probably completely fix your issue.