When my computer is idling, as in, I have closed all web browsers, all internet related programs… just staring at my desktop with no other programs running… I am maintaining a steady 4-4.5kps download rate on my 56k modem.
I have tried downloading anti-spyware programs, but it’s not detecting anything.
Do you have automatic Windows updating turned on? Could it be your antivirus program doing an update? Could it be your ISP downloading updates for its software? Does your ISP’s software try to achieve the illusion of greater speed by anticipating what you’re going to look for next, and caching pages? Of course, most of these would do their bit, and then stop (though the Windows update, if you haven’t kept up with it, could take an ungodly long time).
I’d recommend getting a simple firewall program, like ZoneAlarm (it’s free), so you can at least decide whether programs have access or not.