Please help!!

I'm not terribly computer literate - but I write for a living and am currently having major problems accessing my word docs.

I have Microsoft word 2003 xp

This morning I received a document from a friend, she had proof read some articles that I'd sent her and had highlighted some points. She initially sent me a document in word 2007, but I had trouble opening it (it did not show as a word doc) then she saved it to 2003. I opened it no problem, but thereafter, I have not been able to open any other word doc - including, most frustratingly, my novel (all 43,287 words of it so far) I can't begin to explain how annoying this is.

Every time I try to opne a word doc two boxes open - one says "The command cannot be performed because a dialogue box is open. Click OK and close dialogue box to continue." and the other just says "preparing to install". So, I click OK, but the 'preparing to install does nothing, at all. So I click either "cancel" or the little close box and then the whole Word program shuts. This happens regardless of what document I try to open.

I've tried to restart and I've run all the pending up dates on my computer. I've done some research and some suggestions have been to remove the 'offending' document from my start program. But I have no idea whatsoever what this offending document might be....

I really really really need to get this sorted out and would so appreciate any help you might be able to offer.

Thanks