The Gallery Version 03.00.12 is still beta. But I have run it since it is availible on my live page.
If you have try more times to install and delete, and have old folders still on the Gallery folder you can delete it over the Filemanger. What folder is the actualy you can see in the configuration of the Gallery Module. If upload files is not working it can be on multible thinks.
1. Missing Windows permission in the DNN Folders
2. Missing user permission in DNN File Manager
3. Not allowed file types (see Host settings)
4. Files to large for Gallery settings
5. Files to large for settings in web.config
6. TimeOut for the file upload
If you still have problems after check this you can tray to contact me via Live/MSN messenger.
Regards
Matthias