My Sony Ericsson K660i crashed on me the other day. For some reason it was freezing on start up. Due to this it also meant I was unable to get through the menu to the Master Reset. Unfortunately there is also no key combination or hidden button that might perform this task. This seemed like the only option to resurrect my phone. So I was a bit stuck in how to get it working again. After a phone call to Sony Ericsson I was presented with an option. By connecting the phone to a PC and running the Update Service (it can be found in the support section of Sony Ericssons web-site) I was able to reinstall the software. Even though there was no actual update for my phone I was able to reinstall the current phone settings. The major downside to this is everything gets wiped so all contacts, apps, images stored on the phone are removed. So make sure you keep a backup of these things in case of a crash like this. I would imagine this will also work with other Sony Ericsson phones where you are unable to get to the menu.