I dont know how to fix this. help?

I have downloaded and played this game sucessfully with hacks on multiple mc servers.
I'm even op on some.

Since today i'm recieving this error:
Client error!
The game broke! [java.lang.ArrayIndexOutOfboundsException: 66]
After being 15 seconds online
Oh, and i clocked and it's 15 seconds every time i try

Additional info from the Dos program:
[java.lang.ArrayIndexOutOfboundsException: 66]
at com.mojang.minecraft.e.1.a<unknown source>
at com.mojang.minecraft.e.1.a<unknown source>
at com.mojang.minecraft.1.run<unknown source>
at java.lang.Thread.run<unkown source>

Things ive tried:
-Going online over and over again 15 times
-Reinstalling and repeating the previous thing.
None of both worked.

So any help would be greatly appreciated
Thanks kevin