Word experienced an error trying to open the file. Please try the following suggestions

Someone sent me a Word document today, I tried to open it and the following message appeared:
Word experienced an error trying to open the file. Please try the following suggestions

Reason

Word has blocked a file it thinks might be dangerous. In my case it was a macro enabled document (.docm) but it can also be any Word document, possibly sent as an attachment on a 'suspicious' e-mail.

What you must do is ask yourself a serious question:
Is the file from a trusted source? 

• If yes, then proceed. 
• Otherwise ask yourself whether you really want to open this potentially dangerous file.

Solution
Thanks to Microsoft's knowledgebase I found the solution and the following worked for me. Here's the short version but of course the full knowledgebase article explains more (I've referenced it below).

WARNING: Only follow these steps if you received the file from a trusted source.

In explorer find the document you wish to open, right click on it, click Properties:

Click Unblock, Apply, OK

Now in Word try File | Open, select the document and it should open normally.

For a full explanation please see the following Microsoft Knowledgebase article:

http://support2.microsoft.com/kb/2749199

Version

I'm using Word 2013 but from the article (above link) Word 2010 and 2007 work the same way. 

Conclusion

I know I'm only copying what Microsoft's article already says but I thought I'd post this shorter version as it probably works for most people. The Microsoft article goes into more depth about using the Trust Centre so it's well worth a read if you have a more serious issue. The reason for this seems to be that I received a macro enabled doc (.docm) and Word blocked it to protect me. It's just a click to unblock so once you know this it is pretty easy to 'solve'. Feel free to write your experiences in the comments below.

References

http://support2.microsoft.com/kb/2749199