If you install XenApp 6 on a Windows Server 2008 R2 with Service Pack 1, after successful configuration, you might receive an event entry every time the server reboots that indicates that the filter driver ctxaltstr cannot start “File no found”. Without Service Pack 1, this filter driver is starting!
When XenApp 6.0 production version (RTW) is installed on Windows Server 2008 R2 Service Pack 1, CtxAltStr.sys is deployed in C:\Windows\SysWOW64\drivers.
In Windows Server 2008 R2 RTM, CtxAltStr.sys was deployed in C:\Windows\System32\drivers.
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\ctxaltstr ImagePath still points to “system32\DRIVERS\CtxAltStr.sys”, therefore CtxAltStr.sys cannot be found in the Service Pack 1 environment.
From system32\DRIVERS\CtxAltStr.sys to SysWOW64\drivers\CtxAltStr.sys
If you are using this workaround, it is necessary to reset the registry value with the original path and reboot server, before you use the new resolution. If you apply the new resolution without doing that, the system may be corrupt.
Running the following command copies CtxAltStr.sys into the correct path:
c:\Windows\SysWOW64\rundll32.exe SETUPAPI.DLL,InstallHinfSection DefaultUninstall 128 c:\Program Files (x86)\Citrix\Server Resource Management\Memory Optimization Management\System32\Drivers\ctxaltstr.inf
c:\Windows\System32\rundll32.exe SETUPAPI.DLL,InstallHinfSection DefaultInstall 128 c:\Program Files (x86)\Citrix\Server Resource Management\Memory Optimization Management\System32\Drivers\ctxaltstr.inf
Hotfix XA600W2K8R2X64064 and later address this issue (available for download upon request). Note that the reason why the hotfix is not publicly available is that it has not undergone the amount of regression testing required to make it publicly available.
As of now, XA600W2K8R2X64068 is publicly available for download CTX129741 – Hotfix XA600W2K8R2X64068 – For Citrix XenApp 6.0 for Windows Server 2008 R2 – English
While the issue occurs on W2k8R2 SP1, there are cases where the same issue has been observed on non SP1 environments, particularly if KB2393802 had been applied, which seems to be causing the problem and is included in SP1. However, the Microsoft hotfix 2393802 might not be the only hotfix that exclusively causes the behavior.