MS Office Professional Plus 2010 , Word not opening

I have Microsoft Office Professional Plus installed on my Windows Vista. It was working fine and I was super satisfied with till it started giving me unseen troubles. Whenever I try opening Microsoft Word, it gives me a weird kind of error: 'This file does not have a program associated with it for performing this action. Create an association in the Set Associations control panel.' At times, I also get ‘This application has failed to start because the side by side configuration is incorrect.’ as an error.

I got your issue. The 'This application has failed to start because the side by side configuration is incorrect.' error is typically associated with a missing/damaged Microsoft Visual C++ Runtime Library.

1. Open Registry Editor by clicking the Start button and typing “regedit.exe” and press Enter
2. click Continue.
3. On the left side, expand the tree structure until you find the registry key that starts with "HKEY_LOCAL_MACHINE\COMPONENTS\Winners\x86_policy.9.0.microsoft.vc90.crt_".
4. Select the 9.0 registry key.
5. In the right side pane, make note of the number you see in the Data column for the row where the Name is set to (Default) in case you need to revert to this number later.
6. Double-click the (Default) string value to open the Edit String dialog box.
7. Replace the number in the "Value data" box with the number you saw in step #5. Click OK.
8. click Exit to close the Registry Editor.

After completing step #8 the issue may be resolved. If you continue to see the same problem, restart the computer. You may also need to follow the steps below to correct the file association error message.