Most of your questions are answered in the PM I sent you.
No, it wasn't originally a trial version.
WRT my serial number: what do you mean by "Have you tried updating it?"
The serial number is officially registered to my customer ID at Autodesk, and in fact it was pre-registered to my name before the DVD installation package was sent to me. i.e. the DVD package has a printed sticker on it with my serial number displayed on a yellow label.
I created case number 07027816. Our Product Support team will be contacting you directly with regard to your request.
Thank you very much for the details.
Have a nice day!
This is the official solution provided by Autodesk Support:
We are aware of the issue with the Serial number display with licensed versions of 3ds Max 2009. The issue does not affect the licensing and should not cause issues in usage of the software which has been correctly activated and licensed by the user.
It is possible to resolve the issue by editing the Windows Registry- which will allow you to input the serial. This is also useful for us in keeping a record if you ever need to submit an automated customer error report(CER) from 3ds Max and is recommended- To resolve the issue please follow the steps on the following page on Autodesk.com-
As you are using win 7 64 bit the location is slighty different than mention in the technical solution the rest of the info is same HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Autodesk\3
It worked for me