I'm having issues, but I'm not sure they're related to SL.
TextEdit was my default app for Word files. For this test, I changed to Pages. Several .doc files opened fine. Several didn't, and they appeared to be older files. Most, if not all, of the newer files (2007 and later) opened fine in Pages. A couple I could open in TextEdit. One or two opened in Bean. Some of these files I haven't opened in ages, so it could be SL, or maybe even Pages that's at fault.
Shot in the dark: You could try doing a Get Info on one of the .doc files and changing its default app to TextEdit. Then try changing the default app to Pages. Whatever part of the OS that sets default apps might need a polite nudge to wake up.
If that doesn't help, you might try
icWord. You can convert all your existing Word files to RTF within its 30-day trial period.
If this really is an SL problem, hopefully it will be resolved in 30 days.
mt