The old adage of when your pointing one finger at someone else there's three pointing back at you holds true here too. The first things to look into when your having any sort of trouble are the things you would look into if you were having any other problem. Things like extension conflicts, corruption on your hard drive, or incompatible software versions have caused more of the problems I've seen than any specific internet related issues. So try running with minimal extensions , run Disk First Aid to check the integrity of your hard drive , and make sure that you are using the current versions of all the software you are using. Extension Conflicts can be responsible for any number of complications.
Many times eliminating un-necessary extensions can be a good step towards better web stability.
Hard Drive Corruption can also be the cause of many problems including problems with web stability. In general everything you see on a web page has been copied from someone ease's computer to yours. Every picture and the text of every web page is usually stored on you hard drive if only for a short period of time. If for some reason Corruption on your hard drive causes problems reading or writing one of those files a crash may be inevitable. If you keep having to fix the same problems time and time again that may be a sign of deeper issues going on.