Freeze in Nether

Game freezes in the Nether. Occasionally it can run for a couple minutes, others a couple seconds.

I have deleted the .minecraft folder already and redownloaded all the files, but this did not remedy the problem.

Launcher gives this:

Client> #
Client> # A fatal error has been detected by the Java Runtime Environment:
Client> #
Client> #  EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x00000000026cbfd3, pid=5128, tid=3228
Client> #
Client> # JRE version: 6.0_32-b05
Client> # Java VM: Java HotSpot(TM) 64-Bit Server VM (20.7-b02 mixed mode windows-amd64 compressed oops)
Client> # Problematic frame:
Client> # J  ata.a(DDD)Lasz;
Client> #
Client> # An error report file with more information is saved as:
Client> # C:\Users\Steven\AppData\Roaming\.minecraft\hs_err_pid5128.log
Client> #
Client> # If you would like to submit a bug report, please visit:
Client> #   http://java.sun.com/webapps/bugreport/crash.jsp
Client> #
Client> AL lib: (EE) alc_cleanup: 1 device not closed
Game ended with bad state (exit code 1)
Deleting C:\Users\Steven\AppData\Roaming\.minecraft\versions\1.6.2\1.6.2-natives-336837507028562
Couldn't delete C:\Users\Steven\AppData\Roaming\.minecraft\versions\1.6.2\1.6.2-natives-336837507028562 - scheduling for deletion upon exit