SmartFTP is excellent, but different FTP's won't necessarily solve the problem.
If you have access denied then either there ARE remaining files in the folder or you don't have permissions to delete it, or some other process is still running that is linked to that particuar folder.
Just because you can't see the files doesn't meen they are not there. There are most probably hidden files in the directory (such as Frontpage Extension files (_vti8)) that you will need to remove first.
Additionally there should be settings in your FTP agent that will give you the ability to view hidden files.
That said, if you do have frontpage extensions installed on your site, then you shouldn't be using FTP to access it.
Cheers,
Andrew