My pc is running at 100% cpu while idle

It is possible that you do have a virus. It is also possible that you have a hardware issue.

Having your CPU run at 100% can result in high temperatures, which could result in freezing. You need to discover the source of the 100% first.

BTW: your post will be a lot easier to read if you distribute your punctuation throughout your post, rather than saving it all for the end of the post  

^ +1

When you experience 100% load while not doing anything, go into task manager and tell us what is hogging so much cpu time.

No computer is invincible to computer viruses, even if it never sees the Internet. Like what soest009 states, I would recommend going into Task Manager to see what program(s) are hogging up all the CPU. Software conflicts, especially the case of 2 antivirus or antispyware programs running simultaneously, can easily cause excessive CPU usage. With high CPU usage comes high temps. If the temps get too high, the system may shut down or even freeze. A hardware conflict can also cause problems, mainly on the freezing part (especially the case in the BIOS). Check the device manager for conflicts. If you can't check the device manager for conflicts or no conflicts are indicated (you'll see an exclamation in a triangle icon when a problem is present, though not all problems are troublesome (such as drivers not being installed)), try removing a piece of hardware one at a time until you find the culprit. Start with noncritical components like the sound card, TV tuners, CD/DVD-ROM drives, and others. If those don't work, remove all but 1 of the memory modules. Then, take that memory module out and put one of the others in.

100% cpu usage means that their is a heavy programs that run on your system go to task manager and look for the processes their which programs run heavy. try to uninstall it. and retart the machine,,, and see if their is a changes if not, you system might have a malware or virus, try to scan the whole pc... hope it works for you...