Re: MS Word and complex documents
I don't know if this will help the situation, but sometimes Word documents can get quite 'bloated'. Copying the entire contents to a new document (Ctrl-A, Ctrl-C, Ctrl-N, Ctrl-V IIRC) and saving this one might clean up the document's internal bits and save some diskspace.
It could be worth trying this, to see if the new document with same contents displays the same behaviour.