my laptop is clearly hijacked!

Hello:

I have a dell laptop, running windows 7, 64-bit. Something is clearly running in the background that shouldn't; CPU usage sometimes jumps from like 3% to 53, 80, even 96%, but none of the processes in task mgr are hogging it. The cpu usage is fluctuating between dmw.exe, explorer.exe, apntex.exe, and a couple others, but those combined dont exceed 6% of cpu usage. Its something hidden. Its so bad that for example, if I click on the start menu, three minutes later it pops up. Then I may have to wait another full minute to be able to select anything. Then programs may open, or may not. I have already followed the steps in the "computer running slow" section, despite already knowing the difference between what I'm experiencing and a computer that's just "slow." I just wanted to eliminate any possibility that it could be something simple, so I wouldn't waste your time. The kids used to get on this laptop when my wife had it, and I thought I wiped all foolishness from it when she got a new one and I took this one. When I open the computer in safe mode, no problem. I'm running I was just about to say im running avast antivirus, and when I went to try and check the version, I noticed that it ISNT RUNNING. that's the first time that happened. Three days ago it disabled all the avast scanner settings. Now its just closed!!!! I wait for help, with bated breath.

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