I have the exact same problem.
In December 2013 I purchased the Adobe CS6 Master Collection for educational purposes. After using it for a year without any problems I suddenly got the message that my serial is invalid.
My serial is a Registered Product in my Adobe account.
Tried:
- Uninstalling ALL Adobe programs and reinstalling (3 times)
- Uninstalling ALL Adobe programs, used AdobeCreativeCloudCleanerTool and reinstalling again (2 times)
- Uninstalling ALL Adobe programs, used AdobeCreativeCloudCleanerTool and reinstalling again with a different admin account (On advise of Customer Support)
- Uninstalling ALL Adobe programs, used AdobeCreativeCloudCleanerTool, deleted the SLStore folder and reinstalling again
SarafinaNL : did your problem get solved?
Ashubijalwan1 can you contact me as well?