We get occasional reports of this error, and we have tried really hard to fix it. The trouble is that it only effects some Firefox installs and not all. So we can't even test it. Our installs work fine.

For instance here's mine that works and doesn't reproduce the bug you have:

Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3

Our solution to this is going to have to be a full rewrite of the jam station. This will take some time.

Meanwhile, if you use internet explorer it will work fine for you.

Jon