So here's my problem:
Whenever I try to open Minecraft, the game itself fails to run and freezes my computer until I close it via the task manager.
Specifically, the launcher will pop up complete with the news feed and login as normal. Upon logging in, the window will temporarily turn black and then show the "Mojang" splash, as normal. A moment later, the splash disappears and the screen goes black again, as normal. However, Minecraft will not progress beyond this point; I'm left with a black screen where my game should be, and my computer is mostly frozen (the mouse cursor still moves and I can still open the task manager via Alt+Ctrl+Delete, but my laptop is otherwise unresponsive).
When I attempt to play in the browser, the game screen turns white rather than black, but freezes my computer just the same as with the launcher, and the game screen remains white.
I've tried re-downloading the launcher from Minecraft.net, which seems to have had no effect whatsoever.
Other info that may be important:
The game has worked fine for me since 1.3.2, and worked fine shortly after the 1.4.5 update.
The problem started around the same time as the "MineCon Over" headline appeared on the news feed.
I'm currently running Windows Vista.
I deleted all versions of Minecraft and deleted/uninstalled all versions of Java and downloaded the latest version of each. That didn't make any noticeable difference. I've retried with both the Launcher and in the browser.
(I don't mean to sound like a total and complete novice, but does one need to uninstall Minecraft? It doesn't appear with the other programs in the area of the Control Panel where programs are generally uninstalled. Is there somewhere else I need to go to do that?)
There is no crash log I can find, even using Magic Launcher.
One more (dreadful) idea popped into my mind to try. I went into the ".minecraft" folder where all the data is stored and deleted it. I lost everything, but the game runs again. There's probably a better way to do this, but it worked for me.
Oh well. Better get to punching trees for the time being...
Anyway, thanks for your help. I really appreciate you taking your time to assist me.