Hi All,

My computer wasn't booting, saying something about drive not accessible so took out HDD and plugged it into another PC, it tried to run chkdsk but wasn't allowed because "corrupt master file table". Tried to access it on another computer and came up with "Disk structure is corrupt and not readable". I have since formatted the HDD, read another post on this forum as to how to recover files and fix the problem but what i really want to know is, WHY DID THIS HAPPEN? And how can i prevent it from happening again? Is my HDD on its way out and need to be replaced? Did i do something wrong cause i only formatted it about a week ago due to viruses...

Any help greatly appreciated!

I would replace that hard drive, then save the exisiting one for saving data or special projects... but beware that you may have some other serious, but intermittent, problem with the computer... Likely a power supply, or cable jack, or other issue.
You didn't tell us the age of your system, or brand, or brand or hard drive. It is always easy to speculate about the computer of somebody else...
You can possibly prevent it by spending some money for an uninterruptible power supply with battery that connects between your computer and the wall, being sure you have a quality power supply, assuring that all people who use that computer follow good procedures for shut down, backing up your data religiously, installing more memory than you need, replacing your optical drive every year whether it seems bad or not, and thinking pure thoughts.
Good luck to you. If anything goes awry, please let us know.

Editorial Revision... I should have said
Most major makers of drives have
... utilities for doing a thorough check of your drive.
I would start by downloading their utility package, and running it on the drive.
It should tell you if the drive is repairable.

Why did it happen? All this points to the need to backup your important files!
1. Sometimes even new hardware fails.
2. All hardware fails eventually.
3. Malware can cause failures such as you describe .
4. Environmental factors can cause failures... (temperature extremes, g-forces, etc)
5. Power interruptions (surges and brownouts) can be detrimental. (per Raybay!)
6. Disconnecting a usb drive without using the "safely remove hardware" applet at the lower right corner of your screen is an almost certain way to ask for trouble.
7. etc

Good Observation in next post. Thanks Raybay!

Unless there have been recent changes, I have not seen USEFUL utilities for Toshiba, Samsung, or Tri-Gem drives... Guess I will go take another look... but your suggestion is a good one... as the Seagate, Hitachi, Western Digital, and Fujitsu utilities are helpful... but not always reliable... e.g. Seagate "recertified" drives, and Maxtors.