Latest effort. On Opera. Removed the Mudcat cookies in Opera Tools. They seemed gone. Couldn't reinstall them from Mudcat. Mudcat was still the same, with no 'search' box in the top left corner of forum page and no submit button on the Reply to Thread box. Other links missing, too.
I used Add and Remove to uninstall Opera and right-click-delete to remove the desktop shortcut.
Reinstalled Opera 10.53 from yesterday's download.
What!!! Still had the Speed dial page complete! Still couldn't download cookies. Still no Search Box nor Submit button

To Hell with it. Downloaded and installed Firefox (on that now.) Asked it NOT to import cookies.   Mudcat cookies reinstalled and working, as you see.
Oddly, when I first used Firefox to visit this forum, the Search Box was there!
I'm going to remove Opera file-by-file from Search.