I am using 1.5.6 on a buffalo wzr-hp-g300nh and one thing i have noticed, although really a cosmetic issue, is that when i click edit on any of the default listed service classes and change a value within - or not edit a value, doesn't matter - then click 'close and discard changes' then it puts me back in the Services Classes area in the webif - expected behavior - but then when i click edit again on another rule, or even the same one, it will open another tab to edit the rule, but it has no values inside to edit, nor does it give the options to 'close and apply' or 'close and discard'. I have to close the tab out and log out of the web session and re-login, then it works fine again, and this happen on both upload or download Service classes.
I have tried multiple web browsers as well (IE8 and firefox and chrome) but it doesn't seem browser related as it seem to affect all 3 browsers. Like i said, more of a cosmetic issue with the webif than anything because after log-out then re-login, works again with no problem.