My exchange 2007 users stopped receiving email today. I went through the troubleshooting assistant and it failed the exchange mail acceptance test with error 4.3.1 insufficient system resources. The drive where the mail store is located has plenty of space, so I poked around the web and found out I needed to edit the edgetransport.exe.config file to resolve this. Apparently changing enableresourcemonitoring from true to false will do the trick. Only problem is that when I make the change, I can't save the file. I get "cannot create the C:\Program Files\Microsoft\Exchange Server\Bin\EdgeTransport.exe.config file. Make sure the path and filename are correct"