Originally Posted by Explorer.exe Uses 100 Percent of the CPU solution

View products that this article applies to.
SYMPTOMS
When you right-click an item (such as a file, a folder, or a network connection) in Windows Explorer or in My Computer, other programs may temporarily stop performing a task. For example, a video that is being played in Microsoft Windows Media Player may temporarily stop being played.

If you start Windows Task Manager, you may notice on the Processes tab that the Explorer.exe process is using a lot (or 100 percent) of the CPU resources. To start Windows Task Manager, right-click an empty area on the taskbar, and then click Task Manager.
CAUSE
This problem occurs if the following settings are turned on, and you right-click an item to select that item:
Show common tasks in folders
Fade or slide menus into view
By default, both of these settings are turned on in Windows XP.

If these settings are turned on, information about the selected item is shown in the Tasks pane in Windows Explorer by using an animation. If you open a shortcut menu (the menu that appears when you right-click an item) while this animation is occurring, the animation may not be able to finish (and may use a lot of the CPU resources) until you close the shortcut menu.
WORKAROUND
To work around this problem, select the item before you right-click it. To select an item, either click the item or rest the mouse pointer on the item.

You can avoid this problem by turning off either of the settings that are listed in the "Cause" section of this article. To do this, use one of the following methods:
Method 1: Turn Off the "Fade or Slide Menus into View" Visual Effect
Click Start, and then click Control Panel.
Click Performance and Maintenance, and then click System (or double-click the System icon).
On the Advanced tab, click Settings under Performance.
On the Visual Effects tab, click to clear the Fade or slide menus into view check box.
Click OK.
Method 2: Use Classic Windows Folders
Click Start, and then click Control Panel.
Click Appearance and Themes, and then click Folder Options (or double-click the Folder Options icon).
On the General tab, click Use Windows classic folders.
Click OK.
STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.
The information in this article applies to:
Microsoft Windows XP Home Edition
Microsoft Windows XP Media Center Edition
Microsoft Windows XP Professional
Microsoft Windows XP Tablet PC Edition
Microsoft Windows Server 2003, 64-Bit Datacenter Edition
Microsoft Windows Server 2003, 64-Bit Enterprise Edition
Microsoft Windows Server 2003, Datacenter Edition
Microsoft Windows Server 2003, Enterprise Edition
Microsoft Windows Server 2003, Standard Edition
Microsoft Windows Server 2003, Web Edition
Microsoft Windows XP 64-Bit Edition Version 2002
Microsoft Windows XP 64-Bit Edition Version 2003
Last Reviewed: 5/11/2003 (2.1)
Keywords: kbprb KB819946

Originally Posted by Hydeus

I can also add that AV real time scaner also can provide this type of explorer behavior. If it's "broken" it can scan files "forever", no mater what OS you runing. I that case reinastall (uninstall -> del what rest -> install) AV program and download very latest signatures. Sometimes helps 8)