It’s not uncommon for a friend or a client to call me and complain that a computer has slowed down and taken a noticeable performance hit. Fortunately, I can usually walk the caller through the diagnostic process over the phone.

A few years ago, my first question would have been, “Have you defragged the hard disk lately?” I still advise checking that, but now my first question is, "Have you checked the computer for spyware or virus infection and made sure the system is clean?" I might also ask the user to reboot the computer and bring up Task Manager to look for things that don’t belong. Sometimes, the user has added software to the Startup folder or registry entries that causes additional and unnecessary system overhead.

At this point, I’ll ask if the system shows a noticeable decrease in performance or whether the slowdown happens over time (both conditions require the steps outlined below). Then I’ll walk the user through the application startup. Often, I'll find that application requirements simply exceed hardware capabilities—for example, users loading graphic-editing software onto systems with less than 512MB of RAM (an extreme example) while other applications continue to load as background processes.

I’ve learned to ask about basic system configuration; many users buy discounted systems without enough memory to run business applications, or users will preload so much stuff that runs at boot time that the computer handicaps itself. My experience has shown that the inexpensive hard disks in entry-level computers and storage devices have a notable failure rate, so I’ll ask the user to check the health of the hard disk. The more technically astute have already brought up Microsoft Management Console (MMC) with the Disk Management snap-in loaded and ready to go. The problem is that you can’t trust the Disk Management snap-in when it simply states that a disk is “Healthy." To properly use the snap-in to check the health of a disk, you need to right-click the drive and select Properties, then click the Tools tab and select Error-checking. Then, select both "Check disk" options ("Automatically fix file system errors" and "Scan for and attempt recovery of bad sectors") and click the Start button.

This process can take a long time to run when the disk is experiencing problems. You can also run this process by typing

chkdsk &ltdrive&gt /F

in the command line. Lately, I’ve found disk-corruption errors causing system slowdown in almost 30 percent of the hardware problems I’ve dealt with.

Although Chkdsk repairs often solve the existing problem, disk-corruption errors are frequently an early warning of impending disk failure, so I always suggest a complete backup and careful monitoring of the disk in question. Irregularly occurring hardware problems can often create significant performance hits and should be considered early in the troubleshooting process as a likely cause.

Tip - Fixing Permissions on Shared Folders

I’ve heard from readers and I've seen firsthand that various security and networking applications will make previously available shared folders on a Windows XP computer unavailable to users from other computers, even though it appears that permissions have been set correctly to allow the network shares to be hosted. When you attempt to access a previously shared folder, the system generates a message such as " is not accessible. You may not have permission to use this network resource."

The problem is that the application the user is running has reset the registry value for restrictanonymous to 1 from 0. To change the value back, perform the following steps:

1. Launch the registry editor.
2. Open HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\LSA.
3. In the right pane, double-click the restrictanonymous value.
4. Change the data value to 0.
5. Exit the registry editor.
6. Reboot the computer.