Blocky/Pixelated Video Playback Help

[MejraThea]

Sometime last week my computer started having choppy video/audio, when I played it from a file on my computer/external hard drive. Today, a few hours ago, I started getting what my friend supplied as being "Blocky/pixelated" playback. I have taken screenshots. One / Two

So far I know it happens on YouTube, on Tumblr. It happens on files I play on my computer itself. It does not happen on Netflix, though. Can anyone help me to fix this? Sorry for my first post being this rather than a greeting, but I really need to resolve this.

My information is: Windows 7, Gateway ZX6900, Intel Core i5 CPU 650 @ 3.20 GHz, RAM 4.0 GB (3.80 usable), 64 bit.

[Baldrick]

DOes it happen with every kind of video(avi,mp4,mkv, flv)?

Tried different video players like VLC media player that has built in decoders?

Upgraded Flash media player? Or tried different browsers like Chrome.

[MejraThea]

It happened no matter what in any player or browser. It has now been fixed thanks to the suggestion of someone else, I updated my video card driver. Thank you for the reply, though!