In no particular order:
Try IE8 with no add-ons (All Programs/Accessories/System Tools).
Reset IE (Tools/Internet Options/Advanced/Reset).
Reboot modem, router, and PC.
Right click C:/Properties/"Disk Cleanup" then Tools/Error Checking/"auto fix" and Reboot.
At Command Prompt: "sfc /scannow".
Make sure you are up to date via Windows Update (but don't install IE9 or drivers).
Make sure Flash Player is up to date via Control Panel/FlashPlayer/Advanced/Check Now.
Only if installed update Java.
Only if installed update Adobe Reader.
The steps to download and run the Norton Removal Tool differ depending on what product you have.
Choose your product:
Replace Norton with the free Microsoft Security Essentials.