When you install the software, it is actually installing to your C drive...is your C drive fat 32? That's likely what you're running into...it's not objecting to your external drive...it's objecting about where you're trying to install the progam....
To all users: If your data is stored ONLY on an external hard drive, then it is NOT a backup. A BACKUP is having the data stored in TWO or MORE locations. If it is only in ONE location, you don't have a backup at all. If the data is important to you, then have it stored in multiple locations to prevent data loss.
