So, yesterday, I noticed that my CPU was sitting at 100% (According to Rainmeter and the Task Manager) and I assumed it was a virus. I ran the Avira Live CD and let it do it's thing. After logging back in, it made no difference at all. I then thought my disk drive needed to be defragged. But I remembered that my computer did that automatically every Sunday night. So, I tried to use a System Restore. I selected a point made on July 1 from a Windows Update, and let it do it's thing. When I logged back in, it told me that it had failed. So, I tried again. Same result. So, I opened Task Manager and tried to get something happening. I disabled some non-crucial processes and waited for the CPU to drop. Nothing happened, until I stopped explorer.exe. As soon as it stopped, my CPU went from 100% to 10% or less. And when I re-started it, it shot back to 100. So, I opened the Process Explorer and looked at explorer.exe and I was able to see what was driving up explorer. A .dll, namely ntdll.dll, identified by ntdll.dll!RtlSizeHeap+0x64e was running, twice, each at about 48%. Therefore, taking up 96% of my CPU. At one time. I found out that ntdll.dll is something I don't want to kill, so I have just suspended it, but how can I tame ntdll.dll and bring down explorer.exe's CPU usage for all my other programs?