As the title says, I have a computer here that when its connected to network/internet - it has high CPU usage and runs REALLY slow. Core0 will sit between 50-80%, and core1 between 10-30% when doing nothing at all on the computer. I have ran a full scan with AVG, then read AVG can cause this so I uninstalled AVG and gave Avast! a try. Full scan with Avast! shows nothing. Also gave it a full scan with Spybot S&D, it found a few things to removed but didn't seem to help the speed at all. Also when I first boot the computer up it takes a VERY long time. From pressing the on button its about 7-10min to see the desktop, then another 5-7min after I see the desktop before I can do anything. First 20min or so after I get the desktop up and running tho, the CPU usage stays very high whether its connect to the internet or not. After 30-40min from pressing the start button, if the computer isn't connect to the network, I can start to use it - but even then it runs very slow, and isn't much use having it disconnect from the network . I have turned off any background services or auto starting programs that are not required, and I went through the task manager and killed any processes that are not required (Carbonite, QuickBooks background process, things like that) that I thought might be connecting to the internet and slowing things down. The computer is a Dell Optiplex with WinXp Home SP2. Dual Core P4 CPU and 2 gigs of ram. I know its not a very speedy computer, but up until a week ago it ran just fine for what the book keeper needs to do on it (little bit of internet and email, an QB Pro 2011). Help?