Really sorry to hear about all the troubles you're having. But have you ever thought about using a tab refresher on the login page? I use refreshthis.com and have my page set to refresh every 25 seconds and that usually will do the trick.
As for the Captcha idea....I don't really know how easy it would be to add that, nor if it would really help matters at all. But I'm no expert with that.
The last post was on November 20, 2016, 07:02:21 am.
Nobody has posted on this topic for ages.
Try not to necro..