Huge MacBook Pro Problem - Please Help!

Okay I have so many problems I don't even know where to begin.

I bought my 13" MacBook Pro in August of 2009. Two days after I got it, it completely stopped working. I took it to an Apple authorized repair shop, who told me I had spilled iced tea all over it and it was ruined, never to be fixed again. Long story short, I took it to a different Apple authorized repair shop, only to find out that the battery had leaked inside of it. When I got the computer back two months later, it would only remain powered on as long as it was connected to the charger. I took it back and had it fixed. All said and done, I finally had a working MacBook Pro in January of 2009. (Although much of the delay had to do with me living hundreds of miles from the repair shop).

Fast forward to July of 2011. Mountain Lion, I believe it was, had been released, and I was going to upgrade from Leopard. I worked in a Museum and my boss said that I could use their DVD of Snow Leopard to upgrade, so I could download Mountain Lion through the App Store, since I was using my computer for work a lot and they had a license. I upgraded and I have had nothing but nightmares since. For the past year and a half, my computer is constantly freezing, applications quit unexpectedly, and if I have more than one tab open and happen to do something safari doesn't agree with, I get a notice that "Webpages are unresponsive. Please click continue to force reload" or something along those lines which then forces every site in all tabs to reload but often just causes safari to crash. Furthermore after Safari crashes when I open it again, I have to leave it for AT LEAST ten minutes before the app becomes responsive. However, if I force quit safari immediately after I open it (post-crash), then open it again - it works fine. Weird, I know.

Now I have some really big problems. My computer is constantly going into a kernel panic, where I get the grey screen informing me to restart (and by constantly, I mean I'm shocked I've been able to type this much and not lost it all to a restart warning). Sometimes when I restart as soon as I log in and get the "you had to restart because of a problem, send a report to apple" dialogue, I immediately have to restart again. Sometimes when I restart, I get the circle/slash and it won't turn on. And lastly now, in the last hour (of which I have had to restart twice), it refuses to boot in anything but safe mode. I'm not holding down the shift key.

Oh and another thing of note - it refuses to open some programs, giving various errors; it refuses to allow me to move around files (error code -50); and it refuses to let me empty the trash (error code -50 again). I'm trying to free up a ton of space on my harddrive but it's proving difficult because of my MacBook's refusal to cooperate.

It's all backed up so I can do what I need to do to fix or alter this situation. My boyfriend wants me to just rescue everything from my harddrive and buy an air, but I'm having a lot of trouble considering that because of the amount of issues I've had with both this computer and my iPhone 😟 Bring back the iBook! They were the best.

NOTE: I had to restart my computer twice since I started writing this. Thank goodness for autosave on the apple communities.