Screen Sharing Password Problem

I've got two machines, a powerbook and an imac, both running 10.5.1. I use leopard's screen sharing app routinely. My problem is with iMac not asking for a password when initiating screen sharing with the powerbook. I must have accidently checked off the "remember password in keychain" option when I used screen sharing the first time.

Anyway, I'd rather it asked for a password so I figured I'd just go in and delete the entry from keychain but I can't seem to find it. On my powerbook there's a keychain entry for the iMac pointing towards vnc://imac._rfb._tcp.local. I suspect that's how it's supposed to work. There's no such entry on the iMac. I've also tried resetting the keychain on the iMac but screen sharing still remembers the password and logs in automatically.

I've also tried changing the login password on the powerbook. This didn't seem to have an effect... the iMac still doesn't ask for a password and still logs on automatically. I created a second account on my powerbook and enabled screen sharing with only that account. When I tried to logon to that account on the iMac it asked for the password just like it should have.

I'm really stumped. This isn't a really big deal since both machines are mine but it still kind of freaks me out a bit. What really concerns me is that changing the password on my powerbook had no effect. Any suggestions?

Just tried that (thanks for the suggestion!)

My powerbook did not automatically change the screen sharing password after having changed it on the iMac. It prompted me to enter a password. Oddly, even after having entered the new password, keychain won't remember it and still prompts for it. So I've got one computer that can't forget passwords and one that can't learn them... haha.