This is the step by step proceedure I received from Autodesk Support and as of right now is working prefect.
Can you double-click and open the C:\ProgramData\Autodesk\ACA 2011\enu\Details\Details (US)\AecDtlComponents (US).mdb file?
If not, try replacing it with a copy from a working computer.
If you can open it, it is likely a .NET issue causing the problem in ACA. Re-installing .NET using the steps below should get you going:
1. From Add/Remove Programs, uninstall all versions of .NET Framework including any service packs or hotfixes. Start at the highest version and work backwards, ignoring any errors.
2. Download and run the .NET Framework cleanup utility from the following link. Select all versions and click Cleanup Now.
o http://www.4shared.com/file/eSJ9ymvf/dotnetfx_cleanup_tool.html
If you see any errors when running this tool, keep running it over again until there are no errors.
3. Download and save the .NET Framework 3.5 SP1 installer from the following link:
o http://www.microsoft.com/downloads/details.aspx?familyid=AB99342F-5D1A-413D-8319-81DA479AB0D7&displa...
4. Use these steps to restart your machine in Selective Startup mode:
A) On the Start menu (Windows), click Run.
B) In the Open box, enter MSCONFIG and click OK.
C) Click the Services tab at the top.
D) At the bottom (just above the OK button) click the Hide All Microsoft Services checkbox.
E) Click Disable All.
F) IMPORTANT: In the unchecked list, check the Autodesk and/or FLEXnet Licensing Services back on
G) Click the Startup tab. If there is a mix of checked/unchecked items, make a list of either. Whatever makes for a shorter list,then click Disable All.
H) Click OK and Restart Windows when prompted (just click OK on any permission error you may get.)
I) After rebooting and logging in, click OK to the MSCONFIG Warning dialog.
J) When you see MSCONFIG dialog again, click the Normal Startup button on the General tab.
K) If you made a list in step G, set the Startup tab items appropriately and click OK.
L) Click Exit Without Restart (All settings will be restored at next boot).
M) Click Start > Run. Enter %TEMP% and click OK. Delete everything in the TEMP folder.
N) Empty the Recycle Bin.
5. Run the .NET installer from the download you saved earlier.
6. When the .NET installation completes, test AutoCAD
7. If everything runs okay, restart your machine to get back to normal mode.