I've had problems with Sherlock for a long time. Bought an new iMac G5 in June, Sherlock worked fine. One of the updates (?security update?) seems to have screwed it up. Reintalled Tiger, worked fine, used Software Update & it "died" again.
Started looking at discussion groups this AM. Downloaded & installed the MacOSX 10.4.2 combined update, no good. Got "Pacifist" from VersionTracker & reinstalled the Safari.pkg file, no good.
Tried the suggestion from Ellen posted 10/16 (Go to youruserfolder/Library/Caches/Sherlock/Web Foundations and toss the contents of the Web Foundations folder. Now click on that folder, press Command-I to bring up the Info window, and enable the Locked option.)
I found another post (which I cant find again) that suggested deleting:
User/Library/Preferences/com.apple.Safari.plist,
User/Library/Preferences/Sherlock (the folder), and
User/Library/Cache/CheckPointCache.plist
Sherlock works now, and all my channels are back. I went ahead and "locked" the Web Foundations" folder as suggested above.
Hopefully everything will keep on working now!
Hope this helps.