Graphical Glitch - Stretched Textures

I have been continually plagued by graphical glitches. I've tried every combination of drivers, various settings on OptiFine, settings on the Control Center, but nothing has solved the issue. I've googled and tried about every solution I could find. It doesn't matter what texture pack I use, whether fullscreen or windowed, or whatever. After a few minutes of playing on any server or single player world, I will begin to get these annoying stretched texture graphics that cover parts or all of the screen, as well as "xray" holes in the floors and walls:

Specs / Info:

• i5-2500 / 8GB ram
• ATI Radeon HD 5670 (Latest Driver - version 9.2.0.0, Anti-Aliasing = application defined)
• Java 1.7 64-bit
• MineCraft 1.4.2 + OptiFine

Any ideas or input would be greatly appreciated!