Found some info in another forum that helped me - here's the link
http://dvinfo.net/conf/showthread.php?t=104099
Basically the other post says there's a problem with the AVI plugin. Since I'm not currently using any AVI files I was able to simply remove the aviplug.dll file from the FileIO folder and everything started working fine.
Don't know if this will work for you, but it solved weeks of aggravation for me.