Computer runs at 100% and is painfully slower than ever. Help!

First try to find out which processes are involved:-
1) Stop all your own running processes including the virus scan you started (or wait until it has stopped).
2) Start Task Manager by right-clicking on an empty area on the Task Bar and selecting "Task Manager" from the pop-up menu.
3) In Task Manager select the "Processes" tab
4) Click twice on the header of the CPU column (this sorts all processes by CPU usage - higher ones first)
5) Write down the processes that use most of the CPU
6) Send it to us or alternatively do a search yourself on the Internet for any possible problems with those processes.

The most likely causes of high CPU are:-
- A malicious program (virus/trojan) has infected your system
- A valid program is running and has a bug that causes high CPU
- A valid program is running and simply uses a lot of CPU to complete its task

Good luck,
Ruud

You can use safe mode to fix it.
http://www.keep-pc-clean.com/fix-system-... The safe mode is diagnostic mode of a computer operating system. If encounter emergency of Windows system, you can start Safe Mode and fix it.

Actually most times there is no need to rebuild or reinstalled your PC windows system, what you need is a PC protector. Tuneup360 is good choice, you just need to click one big “fix now” button and get your computer fixed at once.

My pc's browser is quite slow, which always drive me crazy, I want a program to solve the problem, several days ago my friend recommend me a software tuneup360, now I'm waiting for the result. do you guys have any recommendation?