You are opening a can of worms now mate Here is a forum post which may help you out, but bottom line is minecraft is very glitchy, and the best thing to do is try to reduce the strain places on your video/graphics card. That being said, even the best, most up-to-date computer system can still have this issue. All you can do is try to increase the amount of memory java is allocated, reduce render distance and graphics settings and hope for the best. Good luck
When you say you can't access minecraft, what do you mean exactly? the games itself or the game files?
That's what I mean by opening a can of worms, it gets messy and complex trying to solve it. Just a matter or continuing to work at it until you find the solution for your system. What works for one person may not work for others.
Although a higher texture pack may cause you a few problems, you should be ok with a lower res one like 32x32. Have you tried giving spoutcraft a try before?
Sometimes when you try to use an HD texture pack, your computer will run out of memory, depending on how much memory you have allocated to your video card and/or if you have the HD fix. First, double check that you've patched the jar file with MCPatcher ( http://www.minecraftforum.net/topic/232701-11-12w06aupdate-128-mcpatcher-hd-fix-232-01/) follow the tutorial, and then apply your texture pack (only if you are using anything other than default) If this message still comes up, try using the default texture pack. More than likely its your video memory. Try upgrading to a newer and higher-performance video card with dedicated VRAM. Upgrades are never a bad idea I hope this helped and brought a possible solution to your problem! Happy Minecrafting in the Empire!