Any longstanding collection of browser bookmarks is likely to have some that now point to dead URLs. You could find out which ones by clicking each individual bookmark and see if it gets a 404 error--that is, if you enjoy torture.
Here are better solutions for Chrome, Firefox, and Internet Explorer.
[Have a tech question Ask PCWorld Contributing Editor Lincoln Spector. Send your query to answer@pcworld.com.]
Chrome
Try the free Chrome extension Bookmark Checker, by everhelper.me. Once installed, you click the yellow icon on Chrome's toolbar and the program comes up as a webpage.
Here you can change the scan settings; sticking with the defaults worked well for me. After the scan, you can examine the bad links--the ones that got 404 errors. You can check individual bookmarks, or better yet, check the box at the top that selects all of them, then go through them and uncheck ones you want to save.
The Other Errors tab is similar, but with a warning that you should verify items individually. That's good advice. I found sites here that I knew were good and use regularly. On the other hand, most of the sites on the list were ones I hadn't used in years and could easily lose.
When everything you want to get rid of is checked, click Add to Trash queue. Then click the Trash to confirm deletion.
Firefox
Mozilla's browser has a very similar add-on, written by pos1t1ve, with a very similar name: Bookmarks Checker. It's also free.
Firefox's Bookmarks Checker and Chrome's Bookmark Checker are so similar that I don't need to describe this one in detail. I'll just say that it comes up as a dialog box rather than a webpage, and that there's no Trash Queue. When you click Delete Selected from the Browser, it deletes all of the checked bookmarks.
Internet Explorer
I couldn't find a similar add-in for Windows' built-in browser. But I did find a free, stand-alone program called AM-DeadLink. It claims to work for all three browsers, but the add-ins discussed above are better solutions for Chrome and Firefox.
One big problem with AM-DeadLink: The current version, 4.7, will find but not delete broken bookmarks (or favorites, as IE calls them). Why According to the program's website, "As bookmark management in browsers got more complex over the years, it's no longer recommended to use external tools to delete bookmarks. Browser bookmarks should only be deleted within the browser user interface!"
I can see that argument for Chrome and Firefox, but IE stores bookmarks as files in the Favorites folder. It's really not that complicated.
The solution: Use the older version, 4.6, which I found at Major Geeks. It deleted the favorites just fine. And if that scares you, make a backup of the Favorites folder before running AM-DeadLink.