When Windows 7 encounters an error where it can't go on, it crashes. When that happens, it tries to save the parts of the physical/virtual memory that are relevant to the crash in a file that's called a "memory dump" image or just a memory dump. This "memory dump" then can be used by you or a Windows expert to look at exactly what was going on when the system crashed, like a stack trace, what process was running and exactly where in the source code the crash happened. Whether it was in kernel or application code, etc.
This can be useful, since you may have a corrupted program or driver, or bad hardware somewhere, or a program that isn't acting as it should (which may be the result of bad hardware, too), anyways. You can get some helpful things from Microsoft to help in looking at this, including kernel symbols that match your OS, that will allow you to produce a stack trace with symbolic names of procedures and variables that were in use at the time of the crash. There's lot of help with this on the Microsoft Community forums, use Google and find it.
On the other hand, system restore can be helpful for this as well. Like try restoring your system back to the state it was in before it started crashing at all. Or if you can associate the crashes with downloading and installing something, then you can get rid of whatever is causing the problem. Unless you have a hardware problem, of course, then you'll have to deal with that.
This is an improvement, at some point in the past, your computer would just crash (blue screen of death), and you wouldn't get a memory dump that you could look at to try to figure out what happened, what software or hardware was at fault.
There's lots of information on the internet about working with memory dumps and getting symbols, as I mentioned above, in the MS Community Forums and elsewhere. Personally, the first thing that I'd try is system restore, though *smile*.
-Roger