I purchased Photoshop CS5 years ago. I have the box, disc and serial number. I had been using CS5 successfully until recently when after a period of inactivity the software refuses to function and asks for a serial number for CS5 Extended which I don't have and never did. I have tried uninstalling CS5 and re-installing the program without success. I do not need the functions of CS5 Extended. I just want to return to functionally of my Photoshop CS5. What can I do to achieve this?
I am wondering if you have tried to open a PSD or TIF file that was previously edited in the Extended version, perhaps using 3D features? There is no difference between the two versions — the additional features are there, but greyed out unless an appropriate serial number is used.
You could try resetting Preferences, and if that fails, reinstalling, but don't forget to deactivate from the Help menu before uninstalling.
CS5 Extended is the default Trial version. If you click on License this Product and enter your Standard serial number, it should activate as CS5 Standard. If it does not, uninstall CS5, and use the Cleaner Tool to remove the install records that might be giving you this error.
Next after running the Cleaner Tool, download a fresh CS5 installer here:
Download Adobe Creative Suite 5 products and try again. If you use Windows, right-click on the Installer, and Run as Administrator.