We have submitted this issue last week but have not received a resolution. All of the sudden, we were asked to activate our AutoCAD LT 2008 license even though we've been using it for years on the same Windows 7 Pro - 64 bit machine. We did not have any hardware and software changes.
Here is the case number: 08150324.
Though LT 2008 is not supported on Windows 7, I suspect that this may be your issue:
It plagued many installations during that time frame.
The fix probably will help prevent this in the future. Your existing error now is that the automatic system has locked you out.
Get an activation code manually.
You can use the online method to activate your license here:
Or you can can call Autodesk Product Registration and Authorization:
1-800-551-1490 > Option 1 (English) > Option 1 > (Stand-alone)
Asia / Pacific: 65.6735.5688
Europe / Middle East / Asia: 41.32.723.9595
You will need to provide your serial number and the request code.