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(not sure if this is a Superuser question, or a Server Fault question, so please redirect if required)

I've posted this on a VNC mailing list, but I thought I'd ask the folks here as the audience is probably a little wider, and I'm really starting to tear my hair out on this one....

I have been successfully using Real VNC Enterprise Edition Server v 4.4.4 on a Windows XP pro machine within a Windows 2003 Active Directory Domain for around 18 months. I am using Windows Authentication to authenticate clients from other Windows XP Pro client machines. This morning the server ceased to accept connections from any of my client machines, the client machine receiving "An authentication error occurred. See the server error log for details. Do you wish to reconnect?"

I can find no such error log, there are no errors in the windows event log in either the client, server or domain controller machines.

If I disable windows authentication clients can connect.

The effected server machine can connect to other VNC servers on the network (also using windows authentication) as a viewer.

What would cause VNC to stop working in this way?...Has anyone seen this behaviour too?

Thanks in advance,


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migrated from Feb 9 '10 at 13:37

This question came from our site for computer enthusiasts and power users.

Definitely a ServerFault question, hopefully someone with sufficient rep can get the move started. In the meantime have you looked at changes to the firewall on the system VNC Server is running on? – Helvick Feb 9 '10 at 12:07
Fair enoughski, hopefully someone can move it across....I've lost my morning looking at all those different settings!....But I'll give them another once-over – James B Feb 9 '10 at 12:39
Did you try a reboot? (I know, I know... but it is a serious question!) – Chris_K Feb 9 '10 at 14:23
I did....I knew I was in trouble when that didn't work! – James B Feb 10 '10 at 11:25
up vote 1 down vote accepted

AAAHHHHHHHHHHHH.....I have fixed this!....It was because the Windows application log and the system Event logs were full. I've archived them off and it now works fine. Time for a cup of tea.

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It may be a head slapping root cause but it's a good answer. – Helvick Feb 9 '10 at 17:51

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