Symantec Endpoint Security Fan Club - Not!!!!
Over the past 3 months at work, we have came across a number of performance issues and other weird problems related to Symantec Endpoint Security. We finally made the decision to remove it entirely and go with McAfee. Yes, it was THAT bad.
I had a new issue today with Symantec Endpoint Security running on an IIS Server. Every time I made a change such as enabling ASP.NET or deleting the Default Web Site, when I ran IISRESET, I would look back in IIS Manager and the change would have reverted back to the original setting. I deleted the Default Web Site five times and it kept coming back. (Insanity can clearly be demonstrated by the person who does the same futile thing over and over again but expects a different result.)
Once I stopped all of the Endpoint service, I was able to make the necessary changes to IIS. Unfortunately, that is 2 hours of troubleshooting time that I will NEVER get back.