Hi, I am having the same issue with my website. It started about 1 hour ago. I do not think this is a SQL Injection attack as others have mentioned nor do I think this is due to the website being compromised.

I actually think this has something to do with the server and/or IIS injecting this script tag into my website pages. The script tag doesn't always show - just on random reloads.

Also, this tag will show itself on new pages I create that do not link to my database or any other pages and has no functionality.

Having said all that, I don't run the server so I contacted my hosting provider, but in the meantime if anyone has any ideas as to the cause and the fix, I would love to hear it.