If you try and file your company reports from a Macintosh using any of Chrome, Safari or Firefox, you will encounter the following when you try to log in having saved-and-resumed a session:

WebFiling has logged you out as the browser ‘Back Button’ was used or a button was clicked twice. Please re-enter your login details below to return to WebFiling.

Fortunately it was Google FTW:

My solution was to use Opera – the “other” free Mac browser [www.opera.com]. I tested it on the only Annual Return that I have “current” at the moment. That is to say, I started under Safari, then crashed myself out, then went back in and got thrown out in the usual way. So I went back in using Opera and it worked fine … but it is only a single instance and not statistically significant. We need some more evidence that it works!

Opera (non-WebKit?) worked fine, so my reports are in; but sheesh, in this day and age? …