1.7.3 Causes all older versions of MC sound not to work

1. I installed version 1.7.3 and ran with no problems.

2. Ran version 1.7.2 no sound created.

3. Ran version 1.6.4 no sound created.

repeated several times with the same result. It appears that 1.7.3 has corrupted all previous versions.

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I have about 10 versions installed. I have been using 1.7.2 and 1.6.4 with mods. I ran 1.7.3 several time, and then went back to 1.7.2 to compare something. I then noticed that there was no sound. checked my computer and it is ok. I ran 1.6.4 and it had no sound. I can run 1.7.3 and have sound, but no sound with any other version.

I'm going to restore MC from three days ago to see if that fixes the sound

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Restored MC before 1.7.3 and all sound for all versions is back to normal. I'll wait a while before trying 1.7.3 again.