My windows vista (home premium 32bit) frequently crashes. I have very little of an idea why this is happening. It may have been after i downloaded a program, it would have been a legitimate program, as i try and keep my laptop safe.

It crashes instantly seemingly randomly (though i have noticed that the internet, whichever browser may be affecting it).
It can run for long periods without crashing, but gives no warning when it is going to crash.
It has at least two different reasons for crashing, as I have set my laptop to not instantly reset so that I can read the blue screen. One has a line near the top of the screen driver_sqrl_error or something similar. But they both have errors near the bottom of the blue screen with combinations of numbers and letters. They mean nothing to me.
They seem to be to do with memory access, in that a file could not be accessed. It does not tell me which one, or if it does, it is too cryptic.

If this does not give you enough information, I probably have more info if you need it.
Any help would be appreciated, else I must get it looked at, before I lose important work.