Opera "forgets" Proxy Server setting

I have my Opera preferences set to not enable proxy servers, but Opera  
seems to forget this setting and resets it to "Enable Proxy Servers". 
 
This happens while I'm in a session, usually Googling, and when I try to  
go to the Next Page of results, causing a page not found condition.  If I  
hit F12 and reset it, then refresh the page, it's OK (until the next  
time!).  Doesn't always happen, and I can't see the pattern.

Any suggestions anyone?

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