Repeated password prompts for bookmark sync
 

I'm running 10.5 on two machines, and have one set up as a WebDAV server. iCal has no problem dealing with this. But when I put Omniweb bookmarks on the server, Omniweb sometimes gets into a state where it is asking me every few minutes for the password. I've used Keychain Access to make that password entry accessible to all applications, and the modification time is changed (but nothing else) after I (yet again) answer one of these queries. Has anyone seen this problem, and if so, how do you fix it?