Error 1646 - Crashes Game!

So I was cleaning out my closet, so to speak, last week, and I stumbled across Diablo II. I figured I was bored and I decided to install it on my laptop and mess around. Well, I was making a Paladin, when all the sudden the game crashes, and I get an Error 1646, something about an internal error, blah blah blah. Well, I now can't play anymore because that keeps happening. I uninstalled the game, and reinstalled it, and it worked for like 15-20 minutes, then BAM! It started happening again.

I was checking on Google to see what the problem is, and it seems like a relatively common problem, but I don't really understand computer lingo, so I can't figure out what they're talking about when people try explaining how to fix it? I heard it has something to do with the .mpq files being corrupt, and I need to save over the file directly from the Install disc, but I can't figure out how to do it?

Anyone have this problem before, and if so, can you give a lamen a description on how to fix it??