I don't know if this has already been mentioned, but ensure that 'Check for timed out connection' is checked in ALT+O > Connect > Options.
I would have thought this sounds more like a 'Software caused connection abort' situation, in which case an anti-virus could be one of many many causes. Unlikely though if this is a recent development. Perhaps you'd like to check out the suggestions in the
sticky thread anyway?
Regards,
