Windows XP: High CPU usage...

Fix CPU Usage 100%

From http://www.pkblogs.com/100cpuusage/2007/12/100-cpu-usage-while-you-use-internet.html

100 Percent CPU Usage when you run programs after you install Windows XP Service Pack 2

CPU Usage 100% Symptoms

When you run some programs, the CPU Usage meter in Task Manager may indicate CPU Usage 100%. When CPU utilization reaches 100 percent, programs will run very slowly or stop responding (hang) and your computer is freezing or crashing.
Note:Press CTRL+ALT+DEL to view CPU utilization, click Task Manager, and then click the Performance tab.
These symptoms occur after you install Microsoft Windows XP Service Pack 2 (SP2).

CPU Usage 100% Cause

These problem occurs because of the user interface code that is included in Windows XP SP2. The high CPU utilization is caused by the additional overhead that occurs when the IsWindow function is called by the user interface code.

RESOLUTION

Hotfix information

A supported hotfix is now available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next service pack that contains this hotfix.
To resolve this problem, submit a request to Microsoft Online Customer Services to obtain the hotfix. To submit an online request to obtain the hotfix, visit the following Microsoft Web site:
http://go.microsoft.com/?linkid=6294451
Note If additional issues occur or any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. To create a separate service request, visit the following Microsoft Web site:
http://support.microsoft.com/contactus/?ws=support (http://support.microsoft.com/contactus/?ws=support)

Prerequisites
To apply this hotfix, you must have Windows XP SP2 installed.

Restart requirement
You must restart the computer after you apply this hotfix.

Hotfix replacement information
This hotfix does not replace any other hotfixes.

File information
The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel. Date Time Version Size File name
--------------------------------------------------------------
30-Mar-2005 19:53 5.1.2600.2643 577,024 User32.dll
30-Mar-2005 01:30 5.1.2600.2643 1,836,544 Win32k.sys

Disable the Use smooth scrolling option in Internet Explorer. Follow these steps to fix 100% CPU Usage:
1. On the Tools menu in Internet Explorer, click Internet Options, and then click the Advanced tab.
2. Click to clear the Use smooth scrolling check box.

Still do not know how to Fix CPU Usage 100%?

I suggest you try targeted software - registry cleaner to fix cpu usage 100%
Because there are many cases causing high cpu utilization.
1. If you do a lot of web surfing and are concerned about spyware, adware infecting your machine, they will cause system crashes and CPU utilization reaches 100 percent. Some good registry cleaner has the function of spyware & adware removal.
2. You install many beta version of the software, Drivers are not certified, which resulted in many errors, you get high cpu usage.
3.100% CPU Usage while you use Internet Explorer
4. many unneed Startup Program.
5.Others PC Errors. - DLL errors, runtime errors, Windows-Installer Errors, Windows Startup Errors,paths Broken DLLs, OCX, and ActiveX Components all will cause 100% cpu usage. Your PC will run very slowly.

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