To put some more oil on the burning fire:
history of my MacBook Pro 17 inch from 2010 can be read here https://discussions.apple.com/thread/3845903
As you see there was always a problem with the graphic card. Nevertheless it worked flawlessly until last week.
I remember that I upgraded to 1Password 4. Since then I had unexpected crashes of Firefox, Finder and at least also the computer shut down without warning.
When I was installing an upgrade for Parallels the MacBook went down, when I tried to restart it: no volume was found!
I started from an extern hard drive copy, which I had made with Carbon Copy Cloner. With DiskWarrior I was able to save the data but not to repair the intern volume. Also Disk Utility could not do that. So I formatted the intern volume and did an clean installation of Mavericks without importing any user content
As I worked now from the extern hard drive, copying the saved data back to the intern drive, the MacBook suddenly crashed again and I even could not start it from the extern drive anymore!
I went to Comspot (Apple Dealer) where they checked the hardware. No problem was found. Strange enough, when they repaired the intern volume with DiskWarrior it was there again! But the extern hard drive could not be repaired with it.
Now I felt really frustrated and alone. With this hint https://discussions.apple.com/thread/5279792?tstart=0 I was able to save the data from the extern hard drive.
After days of installing a clean Mavericks and installing all Applications manually I am now nearly back again where I was before (did NOT install the 1Password 4, but old version 3)
This is barely relevant to 1Password and more relevant to your Macbook being "old". Your drive is old, and your GPU and likely CPU thermal paste have likely started to, if not completely have, disintegrated (dried into "dust"). To keep that big beast going, you should put in a few hard drive (it would be silly not to go with SSD and make your system feel almost like a new machine) and the heat pipe transfer plats for the GPU and CPU should be pulled up and new thermal paste applied. I suggest doing this as soon as possible before overheating does other damage.
Join #macosx or ##apple on Freenode IRC for help.
I've moved your post out of the other thread and moved it here to the lounge. As @CPngN mentioned, this isn't related to 1Password. A software (excluding firmware) cannot cause your hardware issues, they can make the hardware issues become more apparent but they're not the cause.