I'm trying to install SP3 for LT 2009; when the installer runs I get a message that states "Autocadlt2009lockedsp3.exe is not a valid Win32 application". Is this SP available for all users or do I need a subscription to install it? The software was registered about 18 months ago, and I installed the locked version of SP2 without a problem a few months back. I downloaded and ran the SP3 file twice from Autodesk's site with the same error. Any help would be appreciated.