I have this problem with IE7 in that my favorites (yeah, yeah US spelling) are randomly losing their saved URLs.
Iam using the latest build (7.0.5346.5) and from what i can remember this didn't happen on the last build. It's completely random and bizarre. I will be using my favourites (as i do rather frequently) and then one day, one of them will simply lose the URL assigned to it and thus upon clicking on it the web browser simply does nothing (stays on current page).
Looking at the entry from within Windows Explorer it simply has an address of the favourites folder for that given favourite rather than the URL as per the other favourites entries.
Don't suppose anyone else is having this issue, or better still, knows if there is a fix for it? Nothing more frustrating than losing the URL for a damn good site!