Sessions and/or servers freezing sometimes

One of the most frustrating problems you can experience as an administrator within your Terminal Server environment are occasionally freezing sessions or freezing servers.
The user session or even the complete server is frozen for some time, in worst case the server will not respond anymore and needs to be shutdown manually.

Where to begin when randomly one of your 50 servers will cause your telephone to keep ringing and a bunch of users are forced to have a break?

Indeed, where to begin….
This blog starts where you have done all regular stuff: investigated Windows Event Logging, used PerfMon, Sysinternal tools, checked the last changes, etc.
This blog won’t tell you exactly the root cause (I hope we could), won’t tell you exactly what and how to monitor, but is written from our experience.
With the following tips and enhancements we have solved this problem within many RES PowerFuse environments.

First you have to determine if you are dealing with a central component or not:
Do all users and servers experience the freeze at the same time?
If yes, then you have to focus on network components, fileserver (Home drives, Profiles) or database server (RES PowerFuse, Citrix,..)

If not, do you recognize the following?
- Current sessions become unresponsive
- New sessions hang on “Launching Application” in Citrix splash screen
- The RES PowerFuse Agent Service can not be stopped
- The taskmanager will not start or will hang if already running
- Errors in RES PowerFuse Error log, like:

• Error: (7) Out of memory
• Error: (9) Subscript out of range
• Error: (480) Can’t create AutoRedraw image
• Error: ActiveX component can’t create object

Resolution
Almost all reported freezing problems were solved by applying all next steps together.

1. Install the latest RES PowerFuse Service Release based on the installed RES PowerFuse version (several optimizations since RES PowerFuse 2008 SR6 have positive influence)
   Examples:
   http://support.ressoftware.com/Modules/KnowledgeBase/KnowledgeBaseTreeView.aspx?id=2053
   http://support.ressoftware.com/Modules/KnowledgeBase/KnowledgeBaseTreeView.aspx?id=2285
2. Optimize the server SessionPoolSize and SessionViewSize.Follow the Best Practice in the following KnowledgeBase article, but keep the Microsoft guidelines in mind:
   http://support.ressoftware.com/Modules/KnowledgeBase/KnowledgeBaseTreeView.aspx?id=1858
   http://support.microsoft.com/kb/840342
   http://support.citrix.com/article/CTX112539
   http://support.citrix.com/article/CTX113497
3. Place the MSVBVM60.dll (6.0.98.2) from Microsoft Windows Vista SP1 in “%Program Files%\RES PowerFuse” and “%Program Files%\RES PowerFuse\svc”.The new Visual Basic Runtime dll contains important fixes and enhancements.
   http://support.ressoftware.com/Modules/KnowledgeBase/KnowledgeBaseTreeview.aspx?id=2127