Been there, seen it, complained to Adobe Tech Support too. Their answer was something along the line of “but of course the text may change from Word to InDesign. The page size may be different, the margins or font size may be changed, and InDesign's spacing works differently. It's not reasonable to expect the text to appear in the same place.” They conveniently overlooked the fact that I sent my Word document, the same file imported into ID, and even screenshots with huge red arrows pointing to text that (admittedly) was “not on the same place”.
This issue is the bane of my life. There simply is no reason as to why Word or ID would do this. Sometimes saving the doc as RTF works, but at times a file is literally haunted by it and it keeps on coming up.
I have the faintest inkling of what it's caused by — if you happen to have hyperlinks in that same file, you will see their ID position shifts up first one character, then a couple, then lots. So it seems there is some kind of invisible code inside Word that InDesign refuses to “count”, leading to mis-synchronization of text attributes, and ultimately to bits of text.
You don't mention which version of InDesign you are using, but I would bet it's CS4. In most cases it helps if you import the file into a CS3 version (which does not have this error as often!); but if you only have one version of Id, all you can do is trying to save from within Word as RTF, or perhaps as a slightly older version of Word.