I do most of my editing on a cheap laptop and have no issues, You might just have too many programs running in the back ground killing your CPU. Try turning off all the stuff you don't use(a lot of services/programs start when you boot up) then go into "task manager" (if using windows) and change the priority setting for the software you use to "high". Don't change it to "real time" unless you have a kick @ss computer, but if you did you wouldn't be having this issue anyway.
It does not matter what software you use, Just save after every few minutes so when it freezes you don't loose so much work. Every editor I've ever used crashes at some point. You can get good software for about a hundred bucks, Online versions are much cheaper then buying it from a retail store. I've used all the generic ones, which do a good job but if you get the video bug you will need better software.
I used Sony Vegas(
www.vegascreativesoftware.com/us/?utm_source=sonycreativesoftware&utm_medium=referral&utm_campaign=redirect&lang=us&prdt=vegassoftware)when I started out which I've found to be easy to learn and you can do some good effects(download a trial from there website). I'm hooked on it now and so have upgraded to "Sony Vegas Pro". It's 10X better but also 5X the price, You get what you pay for.
Did I mention....."Save your project on a regular basis".