Close Videopad. Right-click on the launch file and RUN AS ADMINISTRATOR. If still no joy perhaps there are corrupted files.
Close Videopad. Then use this free tool to delete all traces of ONLY Videopad.
When it asks to scan the registry, let it do so. Select all files and delete them.
Then reinstall Videopad.
You might also try another PC, if one is available.
Did that help?