Looks like the FireFox driver is goofing off on duty. Maybe you should switch to the LimousineDriver or even better a FormulaOneDriver if you got that kind of money.
I've run into the same problem and after several days of agony, I was able to find a solution that only involved changing a single character. I'd tell you what that is, but you didn't say it was UGENT!!!, so why should I bother?