Final Cut Studio Keeps Asking For Serial Number

I use an imac. I currently use final cut studio 3. After approx. 2 maybe 3 weeks the software will stop working. It boots up to the registration screen. I will enter my name and the orginal serial number but it tells me the serial number is not valid. What is causing this and how can I prevent? If I unload software and reload, it works but will kick me out again after uses.


Go to the following location: Macintosh HD/Library/Application Support/Pro Apps.
Delete the file Final Cut Studio System ID.
The next tme you launch one of the apps it will ask for your serial number - hopefully for the last time.
If it happens again, something is causing that file to be corrupted, probably by writing its own data there.
Try the above anyway, it might just stick this time.
E: Pat got in first....