Hi

If you suspect software bringing up the issue so uninstall them one by one checking if the error remains. If you got an image, the other way around is the better choice: Installing them one by one by checking with excel.
Google Chrome has been in former time quite a candidate bringing up problems, don't know if's the one.

If the issue did come up all of a sudden, without installing new software, there's a chance that one of the latest updates either OS or Office cause the problem. A reset to a former point might solve the problem.

Just by the way:
I never encountered the problem but using Office 2010 32bit The first thing occuring to me is both of you got the 64bit-version installed. Why - I wonder??? MS itself doesn't recommend the version, actually is advising people not to install this version but stick to 32bit