Whenever you source an operating system, that is not legit, you will have to think twice before trusting it as your main OS or as a file server (as you mentioned). Pirated software can have trojan "backdoors" and can cause more harm than good.
I would go this route but look at getting puppy linux "PC Puppy Rev6, and check to see if the same fault is occurring. generally you should leave 8-10% free on each TB drive in case windows might inadvertently run a scandisk or defrag.
I'm sorry to sound preachy, but your data is worth something to you. I would also look at your power supply.
Purchase a legit copy of XP, or get a linux alternative as you cannot trust that TinyXP a 100%.
The puppy linux distro is packed with utils for your hard drive, can be burnt onto a CD and it is extremely quick and loads into that 256Mb.
I use PC Puppy in the same spec laptop and I have no problems. Heck I never need a reboot and plays Mame perfectly.
