First of all I would suggest force updating your client from the launcher.
If it's a problem with the texture pack and not any mod or anything you've installed:
I don't know how many people know this but the texture pack doesn't require the HD texture pack fixer but it is highly, highly recommended. Some blocks can be very weird if you don't patch it.
Link to HD texture pack fix:
http://www.minecraftforum.net/viewtopic.php?t=46173
Try force updating and then installing the texture pack with the patcher.
Also, if you've patched it in DO NOT change texture pack from the menu in Minecraft. This is where stuff can go very wrong.