Hi,
When I go overboard and run lots of browsers, I too have experience similar issues.
The first thing I do is to look at the error screenshot to see what it looks like.
Most of the time the error screenshot does not show anything odd, sometimes it shows something useful.
When my error screenshot does not show anything I have to guess about what is going on. The page will be slower to load and data will take longer to display.
In this case a throbber that I usually don't see, might be displayed and this is what gives me the element not clickable error. However by the time the error picture is taken the throbber is no longer displayed.
So I add a wait for the throbber and this usually solves my problem.
The problem that you might encounter with your wait condition is that the element might be visible and clickable - passing the wait condition and then a throbber is displayed causing the error.
It can be tricky to fix this.
Good luck,
Adrian.