This is something I found on the Autodesk site.
Issue
There are occasions when Autodesk® software products may experience installation problems after failed installs or uninstalls of other Autodesk products. In these cases, it is recommended that you completely remove all Autodesk products from the system and then attempt the new installation on the cleaned system.
Solution
This solution explains how to uninstall your Autodesk software products and remove any remnants of these products from the system. The end result is a clean system on which you can install your new Autodesk product.
Important: Back up any existing customized Autodesk files before implementing the following procedures.
Uninstall all Autodesk products
From the Start Menu (Windows), click Settings > Control Panel.
In Control Panel, right-click Add/Remove Programs and click Open on the shortcut menu.
In the Add/Remove Programs Properties dialog box, select the Autodesk product to be uninstalled and click Add/Remove (for Windows® 2000, click Change/Remove; for Windows XP Professional, click Remove).
Click Yes when prompted to confirm you want to completely remove the selected application and all of its components.
If you are prompted to remove shared files, click the Yes to All option, and then click Yes when prompted for confirmation to proceed.
After the uninstall procedure is complete, click OK.
Select the next Autodesk product to be uninstalled, and repeat steps 3 to 6.
Repeat the above process until all Autodesk products have been uninstalled from the system.
The uninstall procedure for some Autodesk products requires you to reboot the computer when the uninstall is complete. If this occurs, reboot the computer as instructed and then return to the Add/Remove Programs dialog box after the reboot.
After the last Autodesk product has been uninstalled, reboot the computer.
Remove any remaining Autodesk files
In Windows Explorer, delete the installation folder for each Autodesk product that was uninstalled in the previous procedure.
Delete the C:\Program Files\Common Files\Autodesk Shared\ folder.
Note: If your operating system is configured to store the Program Files folder on a drive other than C, the path listed in the previous step is on that drive.
Remove any remaining entries for Autodesk products from the Windows registry
Warning!
Problems caused by improperly editing the Windows registry could render your computer operating system unusable. Microsoft has provided a wealth of critical information you need to know about the registry in the Microsoft Knowledge Base at
Use the Microsoft® Registry Editor only at your own risk and only after backing up the registry as well as the system.dat and user.dat files as outlined in ARTICLE-ID: Q132332 "How to Back Up the Registry" in the Microsoft Knowledge Base. Additional information about the registry is also contained in the Help topics in the Microsoft Registry Editor.
Log on to the workstation as a member of the local Administrators group.
On the Start menu (Windows), click Run.
In the Run dialog box, enter regedit in the Open box and click OK to start the Registry Editor.
In the the Registry Editor, locate the following subkeys and delete them:
HKEY_CURRENT_USER\Software\Autodesk
HKEY_LOCAL_MACHINE\Software\Autodesk
Exit the Registry Editor.
Reboot the computer.
Each of the previous Autodesk product installations has now been removed from the system
Before reinstalling the Autodesk programs:
Use end task to end any virus-checking programs; disabling a virus-checking program from the system tray may not be sufficient. Virus checking programs may block certain activities (access to the registry, adding/removing/updating DLL files, and so on) that are seen as suspicious, even though these activities are common when installing or removing programs.
Several anti-virus programs can be disabled by right-clicking on their taskbar icon and clicking Disable on the shortcut menu. For more information about disabling your anti-virus software, refer to the vendor for that software.
Important: It is important that you not only disable the anti-virus software but also use end task to end the anti-virus software.
To verify an anti-virus program is not still running in the background as a TSR (Terminate and Stay Resident Program):
For Window 95, Windows 98, and Windows Me:
Press CTRL + ALT + DEL.
In the Close Programs window, select the anti-virus program and click End Task.
For Windows NT®, Windows 2000, and Windows XP:
Press CTRL + ALT + DEL.
Click Task Manager.
In Task Manager, Processes tab, select the process for the anti-virus program and click End Process.
You are now ready to install your new Autodesk products on the clean system.
