Allow only one instance not working (v1.0 Beta)

I am using v1.0 beta and when I select 'Allow only one instance' in preferences then click ok, it does not save, so whatever I do this option is disabled

If a 2nd instance is started (which i do accidentally sometimes) then it just locks up and is unusable and I have to force an 'End Task' from task manager

Can you please fix this option to allow only 1 instance

Thanks

It's disabled if the ESET is detected.

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Why?
How can I only allow 1 instance?

If there is a problem with multiple instances and/or ESET, then cant you default to only 1 instance by creating a mutex or something?

Otherwise ESET is blocking FRD to start properly.

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