Read http://forums.adobe.com/thread/373566 and others. It looks like there are more than one cause here. If this one didn't solve it, then make that call since you have parted with hundreds of bucks and they usually have a patch or tweak at the ready. But only if you call.
i opened photshop today and found out there was a problem with licencing or something so i unistalled using control panel and thought i should just download the latest to see how good it is
installed cs4 extended all when smoothly but got one measly error at the end:
English Language Pack Error: Error 2
so i unistalled AGAIN and reinstalled still same error
there is nothing on my computer stopping it i checked all the processers.please help lots of people seem to be solving the problem randomly on the internet