That's why the recommend going to contest your tickets even if you are fully guilty - if the accusing officer does not bother to show up, you automatically get the ticket tossed.
That's not always the case. I got issued a speeding ticket in Washington over a decade ago. I was given the same advice regarding the officer needing to be present, so I went to court to contest (since I felt I was simply matching the speed of everyone else on the freeway, but was singled out). When I got to court, I was informed by the judge that the ticket (and the writeup) was the only evidence needed; the accusing officer did not have to be present. He read the ticket out loud for the court, which included the other point I was going to bring up to try to weasel my way out of the ticket: if he calibrated his radar gun before and after his shift. He had.
Luckily, the judge gave me a break and waved the ticket due to a paperwork technicality he could have kept to himself if he really wanted to.
Not without a reboot. The values are set at boot time, and the specific file for Ubuntu 9.10 + Wine is
You could always reset it by hand if you don't want to reset by using the method described earlier.