The WD is acting weird. slow/lag and freezes on start up/boot sometimes....I seen that some of these WD Blue's are defective/die pretty early?..... I have a spare Hitachi Deskstar 7K1000 and it works flawlessly....so yeah this kinda sucks...
When you say 'dying' what are you seeing? Have you examined the SMART information? Run short or long SMART tests?
Try downloading some of the tools. I never recommend any myself as I don't keep abreast to what is the latest and greatest, but I use HDSentinal to monitor my temperatures and run short tests.
Are you sure that it's the hard drive and not something on the OS that is causing system lockups? Kinda need more info on here especially since there doesn't seem to be anything mechanically wrong with the HDD.
If there are no SMART errors, and you're having these symptons I would lean to a network/interrupt issue, and not necessarily a disk drive problem. Does the machine boot okay in safe mode without networking? In other words, does it boot faster in safe mode, taking into account that safe mode doesn't boot that fast in the first place?