TermDD Error 50 Terminal Service Sessions Drop

Hello Guys,

We've been having some problems in our school with Thin-client machines kicking students off their session for some weeks now, and it appears to have something to do with an error in the event logs - TermDD Error 50.

The error is:

Event Type:      Error
Event Source: TermDD
Event Category: None
Event ID:      50
Date: 30/01/2008
Time: 17:27:21
User: N/A
Computer:      APPSERVER02
The RDP protocol component X.224 detected an error in the protocol stream and has disconnected the client.

For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
0000: 00 00 0a 00 02 00 58 00   ......X.
0008: 00 00 00 00 32 00 0a c0   ....2..À
0010: 00 00 00 00 32 00 0a c0   ....2..À
0018: 00 00 00 00 00 00 00 00   ........
0020: 00 00 00 00 00 00 00 00   ........
0028: 0b 00 00 00 71 75 69 74   ....quit
0030: 0d 0a                     ..      

I thought it was a networking issue to start with, so we replaced many of our switches. All the clients are connected by 100mb LAN.

We have uninstalled TS licencing from the AD controller (datastore) from which it was installed, removed the x509 certificates (as per KB http://support.microsoft.com/kb/329896) rebooted it and then re-installed Terminal Server Licencing back onto datastore using the telephone method.

This has not solved the problem and I am recieving 'termDD' errors on all 3 application servers.

We have x3 Appservers all running Win2003R2 using Citrix Presentation Servers and several rooms of Thin-Client boxes. There is no rhyme or reason as to which student is kicked off their session. I.e: It's not all the machines in the room, nor it is all users on a specific application server, nor is it specific users.

Has anyone had this problem before? or any idea how I could solve this????

Any help would be great as this is obviously really annoying for the teachers and not very good for the students education!

Best wishes
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nprignanoTechnical ArchitectCommented:
How many thin clients are effected by this - is it just certain ones, or is it all of them at different times?  Also, is this something that started happening recently, perhaps following a server update from Windows or a Citrix hotfix?
nprignanoTechnical ArchitectCommented:
I see in your question that it has been happening for a few weeks, which leads me towards the idea that it is being caused by a specific windows update or citrix hotfix.  If you have not applied any Citrix hotfixes recently, then this may be something caused by a Windows update and subsequently fixed by a Citrix hotfix.  Are your servers up to date with the latest Hotfix Rollup?
matthewsampsonAuthor Commented:
The servers do not have any hotfixes installed (windows or citrix).
Appserver 1 & 2 are accepting clients (but dropping them periodically), whereas appserver 3 is not allowing connections. Our published App is the windows desktop, so when the user enters their credentials and clicks logon, it throws them back at the logon prompt.
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nprignanoTechnical ArchitectCommented:
Is it safe to assume that your Citrix servers were working fine for a significant period of time before this started happening?  I am inclined to think that an a new application that was installed, or an application update that was applied, is the cause of this problem.  

What kind of thin clients are in your environment - are they windows based?  If so, can you try this:

1.      Start Registry Editor (Regedit.exe).
2.      Locate and then click the following key in the registry: HKEY_LOCAL_MACHINE\Software\Microsoft\MSLicensing
3.      Delete the whole MSLicensing key from the registry.
4.      Quit Registry Editor.
5.      Connect to the Terminal Services server.
matthewsampsonAuthor Commented:
The thin-clients are all netbsd clients connecting using ica clients.
Where would the licensing key be stored? the MS KB says to remove the cerificates on the TSlicensing server.
Would the appservers have the license key on them too??
nprignanoTechnical ArchitectCommented:
no, that key would only apply for a windows based thin client.  can you try reinstalling the ica client on one of the affected thin clients and seeing if that makes any difference?
nprignanoTechnical ArchitectCommented:
my other thought is that since you had to recreate the license server certificates, you may need to reinstall citrix, and namely the citrix licensing server component, on any server that you had to reactivate ms terminal services licensing on.

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