What manufacturer & model name is your computer?
Are you running Windows XP SP2?
External HD plugged into front or back USB ports?
Model number of external HD enclosure?
1. You should always have good backups. External HD's are extra storage at best, but they are not the best for more dependable backups.
2. Whenever you think you might have a HD problem, backup all important data to another HD or optical disc IMMEDIATELY (or clone the HD to another HD).
3. Scan that HD with Western Digital's diagnostic tools. It will help to confirm if the HD is failing. Test the drive with Windows XP's HD error checking tools. You can perform these tests with the HD as an internal slave to help in pinpointing the cause.
I have a WD 80GB IDE HDD I bought 3-4 years ago.
Since I now have a laptop I bought a 3.5" external case for my HDD with a USB connection and an external Power Unit before 1 year.
I connected it properly and it works fine.
Usually when it works it makes the spinning noise (the disk works at 7200RPM).
The problem is that sometimes I hear the spinning stop for a second and then restart.
Seconds later Windows display a ?HDD Write failure? message.
When I turn it off and then on again everything works fine!
Please tell me if this is the HDD or the case or the Power unit of the case.
And, that HDD has important data; do you think it might crash anytime and loose them?

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