Check the log, I suspect there will some king of Exception reported in there.
There are things that you can't do at start-up until the device has reached a certain state. This is not a worry at initial installation, because the device is not in startup mode, which might explain why it works on installation but not on restart.
You need to check ApplicationManager.getApplication().inStartup() (from memory).
Check the KB, there are couple of good articles in there that talk about this.
