My 2010 MacBook pro performs poorly and crashes after a couple of minutes if I start it without safe mode. This started after it crashed about a week ago, and I can't use any programs effectively. What is going wrong? Any ideas?

So last week my Macbook Pro crashed, and when I started it up again it barely functioned. Most applications couldn't be opened, and those that did crashed after a few minutes. After a random about of time (from 1-10 minutes later) the finder would start playing up and eventually crash as well. After 3-4 tries, I decided to start it up in safe mode, which works although I still can't use many applications properly (for instance, Pages doesn't show any letters, it just shows a blank document which cannot be edited). Luckily I was able to back everything up while it was in safe mode

My MacBook pro is a 2010 model. I have a feeling this may be related to a prior issue. To give some background, in 2012, it suffered from a broken harddrive which has prevented the computer from doing any kind of repair on the disk utility, but it has continued to function for the most part ever since (although it takes maybe 10 minutes to boot up). I've been putting off replacing it for a while, but I'm guessing its current problems might be related. Unfortuately, even when it worked, some applications didn't function properly, such as the software update program (which crashed when opened). So I'm thinking it might also be some kind of softaware problem too.

Are there any software issues which might be causing this problem? Or is it the broken harddrive?