My MacBook no longer connects to my iMac via screen sharing I have an iMac and a MacBook running Snow Leopard.

I used to connect from my MacBook to my iMac regularly with screen sharing.  Has worked great for over a year.

I recently got my hard drive in my iMac upgraded (from 250GB to 1TB), as far as I know the technician somehow "cloned" the drive, but I really have no idea what the process is.  All I know is the iMac works exactly as it did before, it now has a bigger drive,  except that screen sharing no longer works.

There were two "admin" accounts on the iMac.  "rob" and "user" (user was created by the technician during the hard drive upgrade.

When I connect via screen sharing with "rob/correctpassword" it says something like "connect failure, can't verify password".  As a work around I would try "user/blankpassword", same error, then try again with "rob/correctpassword" and it would work.  I had to do this same thing every time to connect.  Rob-fail, User-fail, Rob-success.

Eventually I deleted the "user" account because I never used it, and now I can never connect as "rob".  Screen sharing is on, and like I said, this always worked before, but there's an authentication error every time.

Does anyone have ideas what's wrong, or suggestions for how to fix this?
Things that have helped me with isolating the failure and eventually getting screen sharing working again:


isolate the network - turn off
WiFi and connect the two machines
with one ethernet cable. This
eliminates ports (other than
internal firewalls), DNS, and
network issues from mis-routing the
traffic.
Turn off screen sharing and remote management and set it up again changing the password to be sure the new password and sharing permissions are set for all users or your specific user.
Watch the logs in console app - the bonjour daemons, screen sharing daemons and network errors are all logged so you might get a clue if a program is having problems accessing a keychain or other issue
Add in a new user to isolate the desired user's preferences and files - it could be something corrupt in the desired user and you won't catch that unless you make a new account to isolate that potential cause.