New hard drive in Mac Book Pro leading to occasional crashes and kernel panics Ok, this is kind of a long story because I don't know what facts are relevant.  

I fell off my bike and my 2010 13" MacBook Pro receives blunt trauma.   It's in a protective sleeve so I don't think about it.  I arrive at school and the computer wakes up from sleep and works, but I can't save anything and it's giving me weird hard drive errors.  So I restart.  Then the computer gets stuck on the Apple start up screen indefinitely.  No matter what I do I can't get it to start up.  

Everything else works fine.  I can run it off of the Mac OS X CD.  The guys at the fake Apple store (I live in Israel) can run it off an external hard drive.  They tell me it's a hard drive problem and give me a way too high price to fix it.

So I buy my own hard drive.  Its a Seagate 750 GB 2.5 inch, but I don't think it's important.

Luckily I had backed up recently to an external HD.  So my sister and I installed the new Hard Drive (easier than I thought!), reinstalled OS X, and then got all my stuff from the back up.

Now everything works well.  Or seems to.  Until Chrome crashes giving me some error about my user profile.  Then when I try to open Firefox it says it can't be opened because it's already open (which it isn't).  Then Microsoft Word gives me an error that has to do with not enough memory.  Then I get long stretches of a rotating beach ball while my computer thinks. Sometimes I also get a Kernel Panic.  

I tried running disk warrior.  I tried running disk utilities.  I tried erasing the hard drive and starting again.  I still get crashes.  I usually restart before I get to Kernel Panics but I can feel them coming.

I don't see any pattern to when it happens.  Sometimes I use my computer for hours straight - streaming music and playing games - with no problem.  Sometimes it crashes right away.  There are no other problems.  I can save files to the HD no problem.

Any ideas?  What else can I try?
Try resetting NVRAM just to be safe. I do this whenever I service a MacBook.

Resetting NVRAM / PRAM
1. Shut down your Mac.
2. Locate the following keys on the keyboard: Command (⌘), Option, P, and R. You will need to hold these keys down simultaneously in step 4.
3. Turn on the computer.
4. Press and hold the Command-Option-P-R keys before the gray screen appears.
5. Hold the keys down until the computer restarts and you hear the startup sound for the second time.
6. Release the keys.

You may also want to make sure your RAM chips didn't dislodge when you dropped it. Here's how to find your RAM bank.

Hope this helps!