Sometimes the registration information on a machine can become corrupted and cause an endless registration loop. This also happens when the user login name is changed or if a machine is changed to log in to a Domain. The following steps should help to resolve the problem.
WARNING: These step will remove registration information for other Borland IDE products as well.

1. Close down Delphi and the Registration Wizard if they are running
2. Browse to the .borland directory in your user home directory. For Windows 2000 and XP this will be located at c:\documents and Settings\<username>\.borland
3. Open the file registry.dat and copy the SerialNumber and AuthorizationKey values stored under “[Delphi 2006]”, this save you the step of trying to remember where you had stored that information. Also make a note of either the UserName or EmailAddress values stored under “user”. You will need these values when you register Delphi.
4. Delete the borland.lic and registry.dat files in the .borland directory. You may also want to move those files to another location that is not on the path
5. Remove the .<Random#A> directories from your User Home (directory name will start with a . and contain 6 or 7 random numbers and letters)
6. Remove the .<Random#>.slip files from your User Home file name will start with a . and contain 6 or 7 random numbers followed by .slip)
7. Remove any activation files that you saved in your User Home. These will by default be in the format of reg*.txt
8. Launch BDS 2006 which will activate the Registration Wizard.
9. Cancel completely out of the Registration Wizard (This is an important step and will write new correct default information to your User Home).
10. Launch BDS 2006 a second time and this time register the product when the Registration Wizard comes up.
11. If you ran the registration wizard too many times, your serial number will get locked out. If this happens go to http://reg.borland.com/bump