Now whenever I open the World of Minecraft client, enter my Minecraft.net account details in,then click 'sign in', wait around 30 seconds, get a 1-5% chance of succesfully logging in; most likely instead I get the authentication error.
Yesterday I didn't have this problem, the chances of login failure were like 2% by the way.
Now I can't fly or speedhack for easier building and navigation...NOTE:
 - Minecraft.net is NOT down, I can access it fine.
 - I am entering my username and password CORRECTLY.
 - My Java version is the latest (1.6.0_26)
 - Running Windows 7 SP 1 x86
 - Tried running the client as an Administrator, still no success...
 - Tried adding a Windows Firewall exception, still no success...