You may have noticed high CPU usage and sluggish performance on your server before.  When you fire up Task Manager you see numerous dw20.exe processes along with the other processes.  It doesn't take too much searching on the Internet to find that those are Dr. Watson processes creating dumps and forwarding them along to Microsoft behind the scenes.  The best way to immediately resolve this issue is to perform an IISReset.  That is only an immediate fix and won't prevent it from happening in the future. 

The first thing you should do on a production web server is to disable error reporting.  To do this, right click 'my computer' and choose 'properties.'  Click on the 'advanced' tab and choose the 'error reporting' button.  From that screen you can choose the radio button to disable error reporting.  You should check the box to notify you when a critical error occurs.    

While I am talking about performance it is also a good opportunity to mention that your production site should be using 'debug="False"' in the web.config.  It can have a significant negative impact on your application as well as the server.  Here is a link with some great information:   http://blogs.msdn.com/tess/archive/2006/04/13/575364.aspx