You may have already tried this but if not then give it a shot.
"Section 2: Advanced Uninstall and Reinstall Steps
If the above steps fail, or you have the same problem in Studio after the uninstall and reinstall procedure, try the following steps:
1.Go to Start - Control Panel.
2.In Windows XP click on Add or Remove Programs. In Windows Vista or Windows 7 click on Programs - Uninstall a program.
3.Select Studio 14 or 15 and click the Remove button (Windows XP), or the Uninstall button (Windows Vista or Windows 7). Follow any on-screen instructions to remove the software.
4.Download and run Regdelete. In the Regdelete pull-down window select Studio 14 and then click the "Clean" button.
If you are having unlock/activation or serial number issues, run Regdelete (http://cdnexpress.pinnaclesys.com/SupportFiles/Regdelete/RegDelete_14.exe) a second time and specifically select "User activation and registration data" from the pull-down list, and then click the "Clean" button. This will clear activation and serial number information from the registry.Note: Only select User activation and registration data if you are having activation or serial number problems. Note: 2 we do not currently offer
http://cdnexpress.pinnaclesys.com/SupportFiles/Regdelete/RegDelete_14.exe for 15.
5.Delete the Studio 14 or 15 folder. By default the location for this is C:\Program Files\Pinnacle\Studio 14. Note: This folder may or may not be present depending on what contents were installed.
6.Perform a Windows search for Pixie. If it finds a Pixie folder, make a copy of it, and then delete it."
Source:
http://avid.force.com/pkb/articles/en_US/faq/en288459
You could also try Revo Uninstaller -
http://download.cnet.com/Revo-Uninstaller/3028-2096_4-10687648.html?c=SEM-SEO&s=fivemill&pid=dlcom_sem&aid=revo%20uninstaller-e&dlc=n&part=fivemill - and see if that helps.