If it happens both with her and with you, it's not a problem on that specific PC, but a feature (bug?) of Word, I'm afraid.
- What version of Word?
- What happens if it's saved as .rtf?
- Why not send it as pdf? You shouldn't send Word-documents unless they are meant to be edited.
Kees
I working as a PC technician in Cape Town, and I have a client that had this word document saved as a template. Not the .dot template, but a .doc that she keeps as a template. She has the problem when she fills in the template, that it wil grow from 200KB to 15MB when saved. I mailed the document to myself in my office to have a look at it, and no luck at all. I tried saving it to a .dot(Template), to another file name.doc but still no luck. After saving it, and compressing it, it will go back to 270KB. But I cant tell my client that she has to send it to everyone compressed. I would like to help her out, but I need someone to help me out..
Thanks in advanced.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic