Adobe Creative Suite 5 - keeps asking for serial number

I recently installed Adobe CS 5 on a Windows Vista laptop. During the initial stage of the installation it did ask for a serial for which I put in the correct numbers. It told me everything was fine and installed.

I then tried opening Adobe Photoshop and it came up with the a dialogue box asking for the serial. I put it in, it gave me the green tick and told me everything was fine. The dialogue box disappeared and then reappeared wanting me to put in the serial, in a continual loop.

I tried serveral logins' including the administrators but none worked. I also tried a reboot.

I must mention that this laptop had Adobe CS3 installed previously which had stopped working due to a licensing error.

After trawling through the internet I initially found this post, and he posts again to say he has found a forum and found the only fix was to delete a database file. He failed to say which file, or even which post he had found!!

After some more looking, specifically for Adobe CS databases, I found this post. It mentions deleting:
C:\Program Files (x86)\Common Files\Adobe\Adobe PCD\cache\cache.db



I found the file, renamed it and tried Adobe again. Put in the serial and it works beautifully.


My conclusion was that this file had either gotten corrupt or had the wrong permissions.