Prism won't launch under XP or Vista. It says "Prism requires Windows 98 (or later)". or "Prism cannot start because the DCOM service (an essential part of WIndows) is not running." or Prism 7 won't launch and presents a message about requiring DCOM.

Prism won't run unless the DCOM service within Windows is running. When DCOM is disabled, Prism can give the misleading message about Windows version. Many programs require DCOM to be on, so this is an extremely rare problem to have.

There are two approaches to fix. Either should work, and the first seems a bit simpler.

Approach 1: Turn on the DCOM service

1. Open Control Panel.
2. Go to Administrative Tools.
3. Then Services.
4. Double click on "DCOM Server Process Launcher".
5. On the "General" tab choose Automatic in Startup type combo box.
6. In the "Log On" tab set Enable for all profiles in the list.

Approach 2: Edit the registry

The following registry string value is used to enable or disable DCOM:

The value of this registry key must be set to Y for Prism to run. If it is set to N, Prism will not run. After fixing the registry, you'll probably need to restart Windows.