Screen sharing stuck on 'Connect...' - but only on one client account. Please help!

Question

I've got a bizarre problem that cropped up sponaneously, and which I can't for the life of me seem to reslove.
I have 2 home machines:
MacBook running 10.6.8  (Server / Media machine)
MacBook Pro running 10.7.4 (Client machine).  Apple Remote Desktop software is installed on this machine, and connections through it work fine.
A few days ago, the sidebar "Share Screen..." link on the client machine stopped working.  All I get is the 'Connecting...' dialog box, endlessly.  The bugger of it is that this is only happening with my main account on the client machine. Switching into another (unused) admin account on the client results in the 'Share Screen...' button working as expected.
I've tried the following cures, found on these forums, to no avail:
Reset PRAM and NVRAM on both systems
updated all software
repaired permissions on both systems
changed bonjour names of both machines
rebooter & power-cycled router
killed the NetAuthAgent process a billion times
trashed all of the preferences, caches, etc. for screen sharing and remote desktop in the afflicted user account on client machine
etc. etc.
As far as screen sharing connection options go, these are my results:
using connect to server (via finder > go > connect to server), and plugging in the address (vnc://192.168.0.103): works
launching /System/Library/CoreServices/Screen Sharing.app, and plugging in the above address: works
connecting via the Apple Remote Desktop software: works
using the "Share Screen..." link from the Lion Sidebar: DOES NOT WORK and results in the stall mentioned above, constrained to my primary user account on the client machine.
As mentioned, this was working properly until a few days ago, and stopped spontaneously, with no changes to either system.
Any help finding a resolution to this would be greatly appreciated; this is driving me utterly bananas .
-Tim
Message was edited by: Timoluka

Answer 1

My wife ran into the very same problem today, while trying to connect Screen Sharing to her media center Mac Mini (server) from a Mac Book Pro (client). I was also unable to connect from my machine as well when logged into my usual account but noticed I had no problem with a Guest User account (as you've described), but had also tried most of the unsuccessful attempts at solutions that you've enumerated.
Then, I read this very similar thread: https://discussions.apple.com/thread/4131788?start=0&tstart=0
...and logged out of our now defunct MobileMe accounts on the affected machines. Upon hitting the "Share Screen..." button again, I was now prompted for a local login and password to the Mini, and once that was input, Screen Sharing connected and started up without any problems! Yes!
Given the similarity of our problems, I hope this works for you as well. My best guess is that Screen Sharing might be prioritizing the use of MobileMe authentication over local logins and passwords, and some of Apple's recent work in decommissioning MobileMe had unexpected results for folks like us.
Jim