Windows 7: CPU overusage Win 7

I have Presario CQ62 laptop, with Celeron dual core CPU at 2.00 GHz, Win 7 Ultimate 32bit. Processes sometimes use 100% of my CPU, when I list them in Task manager, I see that it's not one or two particular process, but several, five or six different processes use CPU, and they randomly (I think randomly, I'm not sure) change their percentage of usage. When I end one particular process, the other, up to that moment inactive process takes his part, and percentage of CPU usage remains unchanged, or varies just a little. I reinstalled my OS, i scanned computer several times, nothing helped. I think it's maybe hardware issue. Can someone help me?

There is no such thing as over using a processor. Using 100% of a processor is perfectly fine!

ZOMG! This program is using 100% CPU!1! Think of the puppies!!11!!1!1!eleven - The Old New Thing - Site Home - MSDN Blogs

You're kidding me. It's not perfectly fine, my computer takes two minutes just to open a notepad document. It's practically stuck when that happens.

Did this problem just start recently, or has the PC always done this?

You can try a clean startup to see if it's some startup programs that are causing the issue.
Maybe it's factory installed bloatware, or some programs you installed causing this?
Troubleshoot Application Conflicts by Performing a Clean Startup

Can you post a screen print of task manager showing the processes that are using all the CPU?
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Update your System Specifications with Speccy, and then copy this information into your System Specifications: Go to your UserCP, and then select Edit System Spec in the left pane. Copy the information from Speccy into the required fields. These System Specifications will then follow your every post.