Hard drives are complex and precision engineered pieces of equipment and saving files on them is a complex business. Sometimes the computer can forget forget exactly where it has saved files.
When this happens, computers slow down as the system has to search for files when it needs them.
To overcome this problem in Windows computers, you can run the Check Disk command. Click Start, Run and type Chkdsk c: /r in the box. On Windows Vista machines click Find and do likewise.
The c: refers to the main disk drive. If you have more drives you can insert d:, e: or whatever. Note this won’t work with CD and DVD drives but it will with external and flash drives.
A black box will appear and if you’ve chosen the C: drive or any other drive that’s in use, it tell you the drive is locked and do you want to run chkdsk the next time you start the computer. Type Y (for yes) and press the enter key.
If the drive is in use as a network or data drive, you may be asked if you want to dismount the drive. Press N (for no) and then Y for the next question.
When you restart the computer a blue screen will appear telling you a disk check has been scheduled and press any key to cancel. Leave the computer alone and let it run.
Be warned this process might take several hours. Once the process starts, you cannot cancel the operation and the computer must not be restarted.
If Chkdsk detects bad blocks on the hard drive, then you should contact your computer expert immediately as your hard drive is probably beginning to fail.