Symptoms

Users connect Citrix ICA clients to a Windows Server 2008-based terminal server that has Citrix Presentation Server installed. However, the ICA clients may crash during the connection process.

Cause

The size of the public key that is used to encrypt Terminal Services Client Access Licenses (TS CAL) is increased from 512 bytes to 2,048 bytes. The terminal server does not negotiate with clients when it uses the new key size. Therefore, the Citrix Virtual Channel for older versions of ICA clients may fail.

Resolution

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix. Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=supportNote The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Prerequisites

No prerequisites are required.

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

Windows Server 2008, 32-bit versions

File name

File version

File size

Date

Time

Platform

Mstlsapi.dll

6.0.6001.22162

84,992

18-Apr-2008

05:30

x86

Windows Server 2008, Itanium-based versions

File name

File version

File size

Date

Time

Platform

Mstlsapi.dll

6.0.6001.22162

232,960

18-Apr-2008

09:29

IA-64

Windows Server 2008, 64-bit versions

File name

File version

File size

Date

Time

Platform

Mstlsapi.dll

6.0.6001.22162

139,264

18-Apr-2008

06:41

x64

Workaround

To work around this problem, upgrade Citrix ICA clients to a version that is compatible with Windows Server 2008.

Status

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

More Information

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updatesThe third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.

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