What are the signs of a FAILING hard drive?

Solution
typically your pc starts to hang at odd times. if you do a large file move, you'll see it stop halfway through and do nothing for a while then start and stop again. Often windows will tell you due to data corruption you need to run chkdsk, and if the hard drive is actually reporting a SMART error windows will inform you that the hard drive is failing (in windows 8 and 10 it will).

understand that many of these issues can be signs of OTHER problems as well, such as virus infestation, driver problems or overheating. so you probably won't know for sure unless you run a hard drive diagnostic.

Windows event viewer in the system event log may start reporting failures on the drive as well (typically hard drive 0)
typically your pc starts to hang at odd times. if you do a large file move, you'll see it stop halfway through and do nothing for a while then start and stop again. Often windows will tell you due to data corruption you need to run chkdsk, and if the hard drive is actually reporting a SMART error windows will inform you that the hard drive is failing (in windows 8 and 10 it will).

understand that many of these issues can be signs of OTHER problems as well, such as virus infestation, driver problems or overheating. so you probably won't know for sure unless you run a hard drive diagnostic.

Windows event viewer in the system event log may start reporting failures on the drive as well (typically hard drive 0)
 
Solution
Hi there gumbob3,

In case you think that your drive is failing, you need to back up all the data stored on it as soon as possible. After that, you can just test it with a tool that can provide a SMART report in order to see if this is the case: http://www.tomshardware.co.uk/forum/282651-32-best-diagnostic-testing-utility
Look for reallocated, pending, uncorrectable sectors.

Apart from that, some of the sign are: overall system unresponsiveness, slower boot and loading times, corrupted data, BSODs, etc.

Cheers,
D_Know_WD
 
Sorry for the late reply.
Yeah, it could be. In case your system can't boot and you need to retrieve your data, my suggestion would be to use some data recovery tool for DOS mode.
You can boot up Ubuntu from a CD or a flash drive, access the drive and back up your data. Here's a thread on Ubuntu Live CD: http://www.tomshardware.co.uk/forum/267999-32-recover-data-mode

After that, you can run startup repair. If this doesn't help, then you will need to perform a clean OS install. Then, you can use some of the HDD testing tools and see what is wrong with the drive.

Cheers,
D_Know_WD