In some Windows 7 64 bit machines, if you have installed the Excel Parameter Hot fix and then Mold flow Licensing Hot fix, it gives the above error while launching Part fill Analysis in Tooling Module of Inventor 2011.
Workaround for this issue
1. Uninstall both the hotfixes.
2. Install the Mold flow hot fix first and then install the Excel hot fix to resolve this problem.
3. If the issue still continues, a repair install of Inventor 2011 could fix this problem.