This forum is for Windows games. I suggest that you call Microsoft.

problems with modern programs running on modern computers is not what we do here

Besides, this is the most generic possible explanation of an "error". You will get nowhere in any forum with only that information, unless you actually try to fix the problem yourself (reinstall office? Hello?) so you run into problems that would be more telling.

Try to run it in safe mode. If it works then it's likely an addon.
Also try disabling antivirus.
You can also try a repair of Office.

I would suggest to open the Event Viewer via right click on Windows 8.1 start button and check it there for appcrash log.

-> Windows Protocols
---> Application

App crash will be listed there with a yellow exclamation mark if it's something wrong.

If someone is that oblivious to VOGONS... might be a bot or spammer

Then calling Microsoft is an appropriate punishment.

I did the following things to try to fix it, but none of them works.

1. Re-installed Office.
2. Update Windows

I agree that it is very strange that you would come to this forum, of all places, for help with Microsoft Office 2010 on Windows 8.1. How did you get here?

I might suspect that you have some kind of virus, but I would expect a re-install of Office to fix that.

Does this error only appear when you double-click on a Word document? Can you open Word directly from the Start menu?

In the worst case scenario ms has a free word viewer
also other office suites can open word files

go get a legal copy of the program then?