Computer crashing while using Adobe Flash Player, Java, or similar

Good day. First I would like to apologise for any errors I make beforehand, as this is my first post.

Anyway, my computer will crash frequently when using some programs, such as Flash, Java, or game clients. And crashing isn't the program freezing or closing, or a bluescreen, my computer is just on one second running contently and off the next. I have a decent enough computer for what I'm doing, I have a 2.4ghz processor and 4gb of ram. I've tried two browsers and a browser-less client, but the issue persists. It's not overloading my computer or something, stuff has crashed with as little as 40% of my CPU being used and only 400kb/4mb of memory being used.

What do you mean exactly that your PC is on one moment and off the next? This surely isn't an apt description!

No, it really is just suddenly off as though the battery was pulled. Though it is a bit odd, if it crashes under normal circumstances (for example blue screen, force shut down) it has a prompt on startup notifying you that it didn't shut down successfully, which doesn't show up when it crashes this way.

Can someone help? This is still an issue

Sounds like a power issue. Check the logs and other System Resources for clues from Troubleshooting Steps for Windows 7.

Post back a screenshot of Disk Management - Post a Screen Capture Image so we can look over the config.

I'd also check over the boot files just to be sure by running Startup Repair