My original cd is ACLT 97. I've purchased all of the upgrades to 2005 (ACLT 2000, ACLT 2000i). My program is corrupted. I've tried uninstalling. I've removed every reference to Autodesk in the registry. I've manually removed every Autodesk file from the hard drive. I reload ACLT 97 and then the 2005 upgrade. The 2005 upgrade only copies three *.dll files and doesn't load the program. How can I clean the system and reload? Why won't the new version load? Formating the hard drive is not an option. If formatting is the only option, I will completely move over to Solidworks. Any suggestions are appreciated.