Hard drive troubleshooting

When you suspect your hard drive is having problems, before you do anything else, check inside your computer to see if both power and data cables are well attached to their slots. Back up your personal data to another hard drive or removable disk.
Try updating your driver. If you have combined hard drives in a RAID, make sure you download and install a RAID driver.
Open My Computer and right click your hard drive. Choose Properties-Tools tab-Check Now (Error Checking). Confirm both checkboxes to perform a deeper scan of your drive, including every bit of it's disk surface. To scan your operating system drive may require a reboot.
If the scan turns up errors, restart your PC and enter BIOS. Enable SMART (Self-Monitoring Analysis and Reporting Technology) monitoring, if your hard drive supports it. Save your changes and exit.
Next use a different computer to download SeaTools from www.seagate.com and install it on a bootable CD-R or USB stick. Boot your damaged PC with the bootable CD-R. Use a PS/2 mouse to avoid problems about navigation in SeaTools. If you dont have one, use "tab", "spacebar", arrow keys and combination of ALT+underlined letter keys (ALT-N for next). After the utility loads, run a full scan of the suspect hard drive. Yellow and Red indicate problems.
If your hard drives has bad sectors, you have lost the files stored on them. SeaTools can overwrite those sectors, meaning that it will erase the data stored on them but also map out the defective areas so that they're never used again. Most drives develop a few bad sectors over time, but if your drive accumulates more bad sector every time you perform a scan, it's probably failing. If so, replace the drive with a new one. Western Digital - Black Caviar or Seagate Barracuda would be my first 2 choices.
If your problem is not about bad sectors, try the next few tips.
Run Disk Cleanup, from System tools, to free up storage space. Make sure that you have at least 1Gb of free space on your hard drive, or Windows will not run properly.
After this, try defragmenting the drive. Also in System Tools, choose Disk Defragmenter. Watch out, defragmenting your operating system drive can cause, rarely, problems such as file system errors.