[X4U] Weird Word errors

[Scott McCulloch]

Using Word X (i.e. not 2004) on OS X 10.4.5

I'm finding that after having Word open and working for a while, I  
suddenly start getting weird error messages.

When I try to save the document I'm working on, I get an error  
message that basically says my hard drive is full (which it's not).

Also, when I try to open other .doc files (some of which I've had  
open in Word very recently), I'm getting a message basically saying  
that it's not a valid Word file.

Sometimes, after this happens a couple of times, Word crashes, after  
which I can open documents I was just told I couldn't.

Is this a known problem?

If so, does anyone know if it's been fixed in the most recent version  
of Office/Word?

I'm trying to meet deadlines to finish my dissertation, so this is a  
bit stressful, and I'll be at the Apple Store in 5 minutes if one  
person says they've had this problem and it's fixed in Office 2004!

Thanks,
Scott