Adobe Photoshop CS5 Could not initialize Photoshop because of a program error [FIX]

Launching Photoshop CS5 on Windows XP was giving a program initialising error with no error codes. Easy fix instructions in this post.

Launching Photoshop CS5 on Windows XP gives the following  error message after loading splash screen.

Adobe Photoshop CS5 Could not initialize Photoshop because of a program error

There are no error codes shown and no errors in windows system or application log.
FIX : To fix hold down CTRL+SHIFT+ALT when you click to launch CS5. This clears preferences and then it all loaded ok.