To fix the invalid picture error for BMP and JPG files in the "CubeTheSphere" program, switching around the tags might not be enough. Ensure that the files you are trying to open are valid BMP or JPG files and are not corrupted. If the issue persists, you could try reinstalling the program or updating it to the latest version. Additionally, check if your computer has the necessary codecs for handling BMP and JPG files.