When a user tries to use software like Photoshop, with a Windows 7 operating system, chances are there that they may encounter an issue and error message saying "you are not allowed to write to the registry". In the same error message, the user will also be asked if he or she wants to continue with the operation anyway. This is not because of the software or the Windows operating system. If one comes across this problem, then it can easily be solved by right clicking on the .exe file and selecting the administrator menu. Photoshop CS4 portable should work thereafter.