Hi Alec!
Well you are in luck.. well kinda.....I don't actually know but still I might be able to help....
 
I am going to say something stupid.... "pity you aren't using Internet Explorer". HAHA! x)
 
The reason? Well, if you open up your Favorites folder in Windows Explorer and change the view to "Thumbnail", Explorer will provide you with a preview of the site for each link, if your internet connection is active. From there you can just delete the links with no preview. Might take a while with your links though ;(
 
Silly question, but are you on the latest version of AM Deadlink? I notice that they have fixed quite a few bugs (like UTF-8 encoding with Opera and some odd cookie problem). FYI latest version is 2.05 (December 2004).
 
Ok time to cut to the chase...an easy way to check your links.
 
This method does have a "limitation" as such - it won't work with IE (hmmm may do if a utility can create a HTML file from your Favs folder...). Anyway, hopefully it will work with Opera. It is nessesary to export your Bookmarks to HTML. I can do this in FireFox via the "Manage Bookmarks" screen. I assume Opera can do it too. Hopefully you will end up with a bookmarks.html file.
 
Now, the easy bit. Download XENU fom here:
http://home.snafu.de/tilman/xenulink.html
 
Once installed, click "Check URL" and point it at your bookmarks file. It works as a spider on live internet sites as well as local files.
 
Job done The only pain in the you-know-what is that the dead links have to be removed manually. At least you wont loose years of valuable bookmarks!
 
I find all link validators to be a bit picky. XENU is really good however it isn't 100%. For example it doesnt seem to like "%" in the URL occasionally.... and some URLS that redirect you get logged as an error even with the option "treat redirect as error" off....I had XENU spidering over 6 million links on my workplace's website! Also, the right-click "show in browser" link is great for double checking the results
 
Good luck!