There are things no one thinks about when trying to figure out why a system is running slow.
When I see Norton mentioned, that's what I think of as a possible cause. Not all security programs are created equal. What works for me may not work for you. It's entirely possible that Norton does not play nice with your system. Even if you have been using Norton for a while and having no problems, an update could make it unfriendly towards your computer.
The only way to find out if it is the problem is to uninstall Norton. IF you decide to try this out to see if it could be a cause download and save the install file for another anti-virus. A list of free antivirus programs is HERE:Freeware Replacements For Common Commercial Apps
Next download and save the Norton removal tool which you can find HERE
I suggest saving them both to your desktop, so they will be right there in front of you when you need them.
If your Norton includes a firewall, it will also be uninstalled. BEFORE you start the uninstall process, enable the Windows firewall.
Uninstall Norton, reboot if necessary, then run the removal tool.
Install the other antivirus.
See if your speed has improved. If it does, great. If not, you can uninstall the new AV and reinstall Norton if you want to do so.
Do you have any toolbars? Sometimes those can cause weird things to happen. My ISP (Comcast) has a toolbar. That one has caused problems for some people-problems which go away when the thing is uninstalled.
Is the system a desktop? If it is, when was the last time the case was opened and the innards cleaned? To much dust build up can affect performance.
Do you clear your cache on a regular basis? Cookies, history, temp files, etc. take up space and if not cleared on a regular basis can affect the speed. If you have more than one person who uses the computer, their cache will need to be cleared also.
When was the last time you defragged? If it's been awhile, or never, clear the cache, then defrag.
You said you've ruled out modem and router. Is the computer connecting wirelessly or is it connected to the router with a cable? Did you plug the computer directly into the modem to see how it runs?
Edited by Queen-Evie, 24 October 2010 - 08:21 AM.