We've had a couple crash reports involving force close on start up. On our end, it looks like a part of the programming language is missing on the device. We've started looking into the issue, and at first glance it appears Train Driver is incompatible with Android 2.2 and below.
We've looked at how to force incompatible phones to be unable to buy the app, but wouldn't work it out. We can do it for individual devices, but not whole Android versions. For now, we'll settle for telling you here and on the Google Play store.
We will continue looking into the error though, and hopefully this will be fixed in future versions of Train Driver. We appreciate your patience with this matter.