A recent issue has come to light :

When trying to launch AutoCAD 2010 as a non-admin user or any other new user whose windows profile was created after AutoCad installation you may get the following errors/warnings:

– Unable to load profile file. Some profile information saved in last session may not be restored.
or/and
– Customization file load failed. File not found: acad
or/and
– Font not found: simplex, Specify Font for FONTALT
or/and
– Missing workspace ribbons

As discussed herehttp://discussion.autodesk.com/forums/message.jspa?messageID=6224260

I can confirm the following fix (as provided by Greg.Toews) works.

If the user’s registry profile is corrupt for some reason you can also just delete it and then start AutoCAD. AutoCAD will then create a default profile from scratch. (HKCUSoftwareAutodeskAutoCADRnn.nACAD-nnnn:nnn)