Preventing Unnecessary Registry Growth in Terminal Server

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One way to keep your registry from growing is to prevent unneeded writes to the Classes key.

The Classes key is located under HKEY_LOCAL_MACHINE\Software, and new users get a copy of the key in their registry at first logon. In most cases, there is no need for this key. Each user's profile is already loaded into the registry while the user is logged on.

Microsoft Office 97 and Microsoft Internet Explorer 4.0 are examples of applications that write to both the User Profile and to the Classes key. Between the two applications, the User's Hive can increase from 2 MB to 10 MB each. To prevent this, you can modify the registry by performing the following steps:

WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.

For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe. Note that you should back up the registry before you edit it.

1. Start Registry Editor (Regedt32.exe), and go to the following key:

   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\TerminalServer\Compatibility\Registry Entries

   There should be two values under this key by default:

   Classes (REG_DWORD) 0x108
   Microsoft\WindowsNT (REG_DWORD) 0x108

2. Add these values if they are missing. These values will disable the per-user file associations feature because the classes key would not be replicated from HKEY_LOCAL_MACHINE to each user's HKEY_CURRENT_USER.