water blocks cause game to become unresposive

Whenever I get close to water the game becomes unresponsive. It does not actually crash so no crash report is generated, but I can no longer control movement or select items. The only way to get out of the game is to use the windows task manager to stop the task. If I can get out of the area of the water, the game then carries on without a problem. The Windows resource monitor has indicated that the problem may be associated with the javaw program, but I cannot confirm this.

Steps to Reproduce:
1. walk near to water blocks or enter water blocks
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