1) Uninstall Delphi 2007.

2) Remove the Program Files\CodeGear\RAD Studio\5.0 directory.

For Windows Vista:

3a) Remove the Program Data\CodeGear\RAD Studio\5.0 directory.

3b) Remove the Program Data\{AB3EC276... directory.

3c) Remove the User\All Users\CodeGear\RAD Studio\5.0 directory.

For pre-Vista Windows OS:

3a) Remove the Documents and Setting\All Users\Application Data\CodeGear\RAD Studio\5.0 directory.

3b) Remove the Documents and Setting\All Users\Application Data\{AB3EC276... directory.

4) If you had the Trial or Enterprise version installed and are now installing the Professional version, then run Regedit and remove the key: HKEY_CURRENT_USER\Software\Borland\BDS\5.0

5) Re-install Delphi 2007.