Long running script?

I'm still using I.E.11 on Win7, with ATT dsl, which is slow enough to begin with, but I keep getting a "long running script" message on several web pages, which eventually goes away, and allows the page to completely load. I have tried ALL the Microsoft fixes, except the ones the blame the firewall and/or virus software. I'm running Norton 360.

Do I have to exclude specific web pages from scanning? How do I do that?

Or exclude folders on the computer, under Norton settings?

Or is this still a Microsoft problem I just have to live with?