Certain Office2007 files crash Win7 explorer

This is a really weird problem. I'm not sure it is directly related to Win7, but I thought I start here. I recently had to rebuild my Dell 531. New HD, Win7 Ultimate loaded over XP. I restored all my files from Mosy. Reloaded all the Office apps from Office 2007 Ultimate.
What I just found is that there are certain Word and Excel files that if I even highlight using Explorer or try to open in the application will immediately crash the application. But, it is only certain files. There may be a dozen files in a folder and only a few will cause a crash. It doesn't take down the computer, only the application - I don't have to click on the file - only touch it. It doesn't happen on PDFs or graphic files (at least not that I found.)
It gets weirder. I used FolderMatch to sync files between my Dell 531 and my Dell 9200 laptop. The very same files that I copied from the Dell 531 to the laptop do not have the problem on the laptop. The laptop is running the same version of Win7 and application programs as the 531.

Any thoughts? Ever hear of such a thing before? Any idea of a solution? (Besides just using the laptop for these file.) It's like my folders have become a minefield and I'm playing minesweeper every time I try open a file - if I guess wrong - boom.

I just wanted to update this post. I ran the Office diagnostic utility. It indicated that my computer was having a problem with it's RAM. No other errors were shown. I downloaded and ran Memtest86+. It showed over 150 errors. The program can't show where the problems are.

I had 4 1GB sticks of DDR2. Two were original with my Dell 531 - no name. The other two I put in about a year ago - Corsair XMS2. I pulled the Corsair sticks out - easiest to get to. I tried to run the diagnostics again. The machine wouldn't even boot. I shut down, pulled the original RAM out and replaced it with the 2 Corsair sticks. I ran the Memtest on the these. It still showed errors, but fewer. I started the system and it booted normally.

The crashes that I was having with explorer, Excel, and Word when I tried to access certain files stopped. The same files that caused the application programs to stop working before, were fine - no problem. Could a problem with RAM cause files to crash a program? Could it have been a file size issue? I didn't check that.

Also, is there a definitive test for the integrity of RAM? So far everything I've used detected errors, but the machine runs.