AutoCAD LT Error aborting 2012

I have been going through and updating our engineers to 2012 LT and have run into a problem with one of our engineers. After rebooting the machine, AutoCAD 2012 LT works perfectly for a brief time, maybe an hour or two. Then if you close AutoCAD and try to open again after this period, you get the following .
AutoCAD LT Error Aborting
There is a problem with the installation and AutoCAD LT cannot continue.
This error may occur if the registry software has removed or altered keys that are required to run AutoCAD LT.
To restore the required registry keys,you will need to reinstall AutoCAD LT using the Add/Remove Program functionality in the Windows Control Panel.
