What version of Hoster are you running? Version 3.319 is the easiest for us to allow transferring to a new computer. If you bought Hoster or a Hoster Upgrade after May 30, 2006, you can install 3.319 free. Go to
http://www.mtu.com/ and click the Downloads link at the top navigation. Then, find the Hoster link and go and download, save to your computer, run the install on your computer, and choose UPDATE. Once 3.319 is installed on the computer you want to remove Hoster from, run the install again and choose the REMOVE option. This will free up Hoster.
Click the SUPPORT link at mtu.com and find the "Web Email Form" link on the left column. Submit that you have removed Hoster 3.319 and need its Registration Record deleted so you can install on a new computer. We're running a few days behind now so please don't expect instant support for this. It is a manual operation.