at this thread, maybe there is a clue there. Try uninstall and reinstall. Post back if this doesn't resolve.
For no apparent reason my desktop has stopped opening PDFs. From time to time I need to download information in PDF form, but now I get a box that says, "I'm sorry, MSN has a problem and must close." It asks me to send the report to microsoft, which I do, and then Explorer shuts down. I've contacted MSN with no help, uninstalled and reinstalled Adobe reader and looked through my drivers to see if I can find the problem. I don't know if it's the software or the PC that's messed up. I run XP and Explorer 7 on a Sony Vaio multimedia PC. Any clues?