ARWArchitect wrote: I have been away from Autocad 2004 for about a year.   Upon beginning to use the program again the following problems occure.   When the program is opened an error code appears reading:   Fail to create CommCntrClientSink Object!   I click ok and 2D work does not seem to be effected.   Except:   When the 'change properties' command is used the program gets a "fatal error" and stops working.       When I try to use the 3D Autodesk features the following error code reads:   Unable to execute the tool.  Class not Registered.   None of the 3D design functions work.  Non of the tool palets work.   This part of the program has worked in the past without problems.       Thank you in advance for any guidance you may have.

This error may occur if third-party programs, such as system registry cleaners, have corrupted one or more of the registry settings during a cleanup process.

To resolve this issue, you must perform a clean reinstallation of AutoCAD®.

To ensure a clean reinstallation of AutoCAD, follow the instructions contained in the following solution:  http://usa.autodesk.com/getdoc/id=TS45252" rel="nofollow - Remove all Autodesk® software products from system to ensure clean installation .