I had this problem with AutoCAD Architecture 2008 that I installed after installing ACA 2009 and ACA 2010 on the same machine.
I got this crash message: AutoCAD Error Aborting FATAL ERROR: Unhandled e06d7363h Exception at 75d0b4f4h. (or FATAL ERROR: Unhandled e06d7363h Exception at 75d19617h) I was advised by the automatic CER email to install the service pack but that didn’t help.
AdLMInfoPath was empty on the following location and was obviously the reason for the crash. After I deleted AdLMInfoPath I was able to proceed with the activation.
Even though the document only talks about 2009 products it seems to affect also 2008 products.
Knowledge Base document: AutoCAD 2009 Crashes During Activation of a Stand-alone License
On the topic there is also a problem with AutoCAD 2010. Knowledge Base document: AutoCAD 2010 does not start. When you try to start AutoCAD, you briefly see the splash screen and the program does not start.
Knowledge Base document also describes how to: Starting AutoCAD® 2010 in Windows® diagnostic mode by enable “FLEXnet Licensing Service” (previously known as “FLEXlm Licensing Service”) instead of as in earlier versions the “Autodesk Licensing Service”.