Flash Player messed up and messing up my system

Even my Yahoo mail is messed up, it keeps crashing due to the Flash Player installed on my system

I have been having endless problems for weeks and cannot find an answer. I have done everything that I have been told to do, everything I have found on all associated websites, nothing is helping. Windows updates, disabling hardware, deleting files, rebooting constantly, uninstalled/reinstalled umpteen times. Nothing works. Even those little windows that come up - enable hardware, and accept/deny - they don't work. The window appears but doesn't matter what I do it will not go away. I have to close everything and re-open to get them to disappear. Even showing up on Yahoo mail. Then Yahoo goes black and will not come back, regardless of what I do. Close everything - yet again. How many times have I lost all my history and points and everything in the past 3 weeks.

Actually it works fine for a short while, from 10 minutes to about an hour. That is all. Then it - sticks, becomes jerky, crashes (Firefox - now using IE, doesn't crash, just stops working altogether), pixelated, etc etc.

Windows 7, Pentium(R) Dual-core CPU, T4400 @ 2.20 GHz, RAM 4G, 64-bit OS

I pay for things to watch but then they become unwatchable. I am heartily sick and tired of fighting with it. My system has been stable for years, why am I now forced to use a product that does not work. This is crap.