I don't know much about this error or where your documents are or what anti-virus software you use. It's worth checking whether you get the error message on pretty much all .docx documents or only on some. If it's only on some, is there something about the location (drive, folder) or contents that could be factor?
What happens if you create a new (test) document in Word, save it and then try to re-open it? Do you get the same message? What happens if you open other file types (Excel spreadsheets, Notepad, photos)? Do you get the same message? If you are able to narrow the down the problem files, it's easier to trace the cause of the problem.
As previous replies note, if you google the error message all the results are about accessing documents in a 'Sharepoint' library. If you don't use Sharepoint at all and you get this error when opening documents on your local drive, then it's just possible that your anti-virus software is not working as it should with Windows/Microsoft (perhaps following an automatic update).
I use Norton but I'm guessing other anti-virus software works in a similar way. In my Norton settings/preferences, the option 'Real time protection' is set to 'on'. This means that Norton always does a virus check on any files, documents or e-mails that I open with any program. It happens so fast that I don't even notice it.
It's only ever happened to me very occasionally in the past but somehow the anti-virus software I was using at the time (Mcafee, Norton) suddenly stopped working properly with Windows. I had to restart, reset or re-install it or reset the standard Windows security settings.
Without knowing the details, it sounds to me as if anti-virus software (either on a server or on your laptop) is trying to do a 'real-time' virus scan on documents you open but failing in this. The gist of the message seems to be "sorry, unable to check this file, use something else instead".
Some anti-virus software products don't work well together with the 'standard' windows security software. If you use anti-virus software, check the suppliers recommendations for Windows security settings. They often recommend turning off Windows security when running their software. Anti-virus settings sometimes 'clash' with the standard Windows security software.
One option is to temporarily disable internet, then do a complete virus scan to check that your Laptop is 'clean'. With internet still switched off, try switching off any 'real-time anti-virus protection' settings to see if the message disappears when you try to open .docx files. If not, close all your anti-virus programs and try opening the docx files again.
Turn the anti-virus software back on and try turning off all 'Windows Security' settings. Check whether the .docx problem still occurs.
If you still have the problem, try turning both the anti-virus software and Windows security settings to off.
If the problem disappears at one of these steps, there's a good chance that the problem's being caused either by anti-virus software or Windows security software and often a combination of the two running together. If this is the case, you can contact the 'support' department for you anti-virus software and get advice on how to fix the problem.
Mike
