Not a very detailed error. Have you turned off "Show Friendly HTTP Errors" in your browser?
Has this code ever sent mail?
check your variables are what they should be, EHG 'emailTo'
Follow the steps in this link:
This line looks dodgy to me:
Set objCDOSYSMail.Configuration = objCDOSYSCon
I would replace it with:
set objCDOSYSMail = server.createObject("CDONTS.Newmail")
Wind is your friend