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VanMagnus Systems
VanMagnus Systems, Mac Support Specialist
Category: Mac
Satisfied Customers: 1136
Experience:  A+ and Network+ with more than 18 years in the IT field. Have worked on MAC's since I was 16.
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Screen sharing no longer works on my MacPro and one of my Macbook

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Screen sharing no longer works on my MacPro and one of my Macbook Pros
From the MacPro I can do screen sharing with MacBook #2 Pros but not MacBook Pro #1.
From the MacBook Pro #1 I can't do screen sharing with the MacPro
From the MacBook Pro #2 I can do screen sharing with the MacPro and MacBook Pro #1

You can see what is happening with this video capture here:
I am trying to do screen sharing with MacBook Pro #1

Thank you
When did this first start? Did you install or uninstall any software just before this happened?
Customer: replied 6 years ago.
I noticed it about a week ago. All that I can think of that's been installed or updated is iTunes 9.2, Onyx 2.1.5, Mac OS X Update Combined
Customer: replied 6 years ago.
I also tried logging into another account with admin privileges with the same result
What is the exact OS X versions of each?
Customer: replied 6 years ago.
10.6.4 all around
Please try:

Turn screen sharing off and back on again.


Edited by VanMagnus Systems on 7/2/2010 at 3:57 AM EST
Customer: replied 6 years ago.
Still no go. I toggled it on and off on both Macs.

OK. Please try this:

1) Repairing permissions. Applications -> Utilities -> Disk Utility
2) Zapping the PRAM:

And for screen sharing, be sure the firewall ports are open in Apple menu -> System Preferences -> Security:
Customer: replied 6 years ago.
Repaired permissions. Firewall is (always) off. Will zap PRAM momentarily
OK. Waiting with baited breathe....
Customer: replied 6 years ago.
Sorry, still no go. Ditto on the Macbook Pro #1. I can share screens from the MacPro to MacBook Pro #2 and vice versa and I can share between the MacBook Pros but still no go with the MacPro to MacBook Pro #1 or MacBook Pro #1 to MacPro. All Macs have the same Sharing Preferences. Oh well, this isn't a critical need as long as I can still share files but Screen Sharing was a great convenience.
Customer: replied 6 years ago.
I just booted up from a June 15th backup and Screen sharing works with that backup.
There is a glitch that Applemis aware of with the upate for the 10.6t.4. Please do not update again until it has been fixed... I am not sure when though. You can contact the Apple Genius Store folks. they will know when.
VanMagnus Systems and 3 other Mac Specialists are ready to help you
Customer: replied 6 years ago.
I found that VirusBarrier X6 was the culprit as it placed the ip addresses of my source and target Macs on it's list of blocked addresses. Removing the ip addresses (from VirusBarrier's Blocked Addresses list) and adding them to the it's list of trusted addresses (in VirusBarrier X6) solved my screen sharing problem.

Not sure I really need VirusBarrier X6 and it's a little too proactive for my tastes.
That is great to know, that is the type of information that is needed to resolve your technical issues. I will take note of this, so if another customer has this same issue. I can resolve it more quickly.

Thank you very much,

VanMagnus Systems.