Sound like a load of horse's to me. MS Office is unlikely to be causing it - there are hundreds of millions of copies in use worldwide.
Just hand it back and say you want a refund. Clearly the PCs are not of 'mechantable quality' because they can't do what you wish to do - run MS Office reliably.
You do not have to put up with c** PCs or c**p service these days. If I was you I would buy one of the better (in my opinion) brands like HP, Dell, Sony, Toshiba, Panasonic. The difference in price is minimal these days and you DO get quality kit.
T, January 2010