First, same circuit in the wall protector is also in UPS.  That
should have been obvious to anyone making a technical recommendation.
Second, anything that would work on computer power cord is already
inside computer power supply ... if computer is not using a 'dumped
into the market to sell cheaper' power supply.

 Power supply's job is to provide disk drive and everything else with
stable voltage.  Disk drive voltage must not vary even when AC mains
cause incandescent lamps to glow at only 40% intensity.  Are your
incandescent lamps dimming that much?  If not, then power supply must
provide perfect power to disk drive - not interruptions and no damage.
Many computer assemblers don't even know how electricity works.  They
buy power supplies only on dollars and watts.  Then all kind of strange
computer problems occur - traceable to a 'good deal' power supply.

 Discovering a power supply problem takes less than 2 minutes with a
3.5 digit multimeter should you personally want to solve the problem.
Swapping parts to fix problems too often means buying most of a
computer all over again.  Is it a power supply or some other part of a
power supply 'system'?  If power supply is good, then and only then are
you ready to move on to other suspects.

 If power supply is not the problem, then a number of other tests or
diagnostics should be executed. Not difficult to perform.  The most
difficult part is explaining the solution and maybe obtaining those
diagnostics.

 Meanwhile surge protector is recommended too often by those who,
again, don't know how electricity works.  Power supplies must perform a
long list of functions.  If not, then numerous strange computer
problems occur intermittently and repeatedly - as computer owner
replaces same parts but again and again without fixing the actual
problem.