Given that youre encountering spurious failures or delayed responses from your computer, it could be the case that:
The hard drive is damaged and struggling to read part of the surface. When this happens the hard drive light on the PC may be stuck on for extended periods of time and there will be no "scrabbling" noises like normal
The powersupply is defective or overheating. When a power supply cannot provide enough power to run all connected systems you can experience crashes, freezing, hard drive access problems
Something else is overheating. When major components overheat, it usually results in a crash/freeze and you cannot interact with the computer at all. It does not usually "come alive" again. Some overheats occur due to dust buildup, thermal transfer pastes drying out and becoming ineffective, sometimes even just a change in the environment the computer is in.
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As a further guidance, if your hard drive is suspected to be faulty you can usually download software from the manufacturer's website. FOr example
http://www.seagate.com/www/en-us/support/downloads/maxtor_desktop/ provides software to test their drives. Additionally, most tools that test SMART reports offered by most hard drives, will test drives not manufactured by the software author. i.e. you may well find that Maxtor SeaTools will happily run a SMART test on your IBM hard drive. Most such diagnostics are free. Some such tools will offer you the option of copying data from one drive to another.