This is pretty unusual. You should not have to reboot the proxy server daily. A few things to check.
1) The Balance proxy runs as a Java service. Do you have the latest version of Java on the Windows proxy server?
2) The Balance proxy writes intermediate data locally. It you have a real-time virus scanner installed on the proxy server, it can cause problems with larger environments, such as yours. To fix this, you can get a virus scan exception for the directories that the Balance proxy is writing to.
I am happy to hear that it is unusual. It means it should be possible for me to fix.
I have updated Java often. I took a look at the antivirus program agan and now I suspect the antivirus program of not bypassing the balance directory as it has been told to so I will dig into that. I have been looking briefly at the log files but I will take another look at them.