After Visual Studio is installed, the default behavior when an unhandled exception occurs is to show an Exception dialog that requires user intervention to either start Just-In-Time debugging or ignore the exception. This may be undesirable. To configure the server to no longer show a dialog when an unhandled exception occurs (the default behavior prior to installing Visual Studio), use the registry editor to delete the following registry keys:
Is there any particular set of actions you take that triggers the JIT? Under normal circumstances (and depending on your configuration, you should not see this unless an application is throwing an unhandled exception of some kind.
You should also be able to tell what executable is crashing.
In any case, there isn't enough information in this thread for us to help you at this point.