It seems the hard disk was unable to spin up properly. In some cases this can be caused by HDD problems (problems with motor, bearing - this is more common for some HDD models). But it can cause a weak power supply which is not able to drive enough power for all components in the computer.
To verify the situation, please check
- the type and nominal power output of your power supply (eg. 350W / 400W etc.)
- the number of hard disks/optical devices in the configuration
- other type of devices using huge load (CPU / VGA card)
and please verify how your devices are connected to the power supply. I mean if you power supply has 2 or more separate power lines, maybe you can modify the configuration to balance the load between the different lines.
Power splitters and converters (eg. standard Molex -> SATA power cable converter) can also cause such problems. If possible, please avoid using them.
You should know that this problem occured many times (otherwise the displayed health would be higher).
The hard disk records all such problems to its SMART table (to the "Spin retry count" attribute). If you verify the above and modify the configuration to fix all issues, the problems will still be recorded so the health will not jump back automatically to 100%.
But then you can check if the "Spin retry count" attribute for a longer period and if it will be constant (does not increase more) then you can "clear" the problems and restore the hard disk health.
For more information, please click on the "?" icon next to the text description in version 2.81 of the software or check the Support -> Help page http://www.hdsentinel.com/help/en/index.html
for more details.