Excel VBA/MS Word Mail Merge Not Working

Hi.
I am not sure if my issue is Excel VBA or MS Mail Merge and so I hope you will be able to assist.
I have created an Excel macro which imports another file, does some fairly basic formatting, validations against other data and then compiles a table for use in an MS Word Mail Merge.
It all worked fine apart from I tried to embed the Word file as an object and received an error message saying 'Word cannot start the converter mswrd632.wpc.' - I am not sure if this has had any impact but it seems to have been from around the same time I have been getting the issue.
When I run the Mail Merge, (I have not bothgered embedding the file, I just open seperately) and I get the 'Mail Merge Recipients' window, the menu bar, for example for sorting, selecting nonblanks etc does not work. The whole bar seems to have become unusable, ie selecting all/none, drop downs do not show. My colleague tried to run the merge on his PC and it was fine, I moved my laptop to a different network point and I was able to get it to work. I then moved back and it continued to work. But then I ran a few processes again and it didn't work again. My colleague ran again and it was ok. I am unable now to use the menu bar on any Mail Merge, even a new Excel table and a new Word document.
It suggests to me possibly something different between the settings on my laptop and the PC but have no idea where to start looking. Does this sound likely or is there possibly something within my Excel code which has caused this? We are a little reluctant to run the code on the PC in case it 'breaks' that as well if it is the code.
Please could you advise of any solutions and what may have caused this?
Thank you in advance.
Richard