Help phone shut down and uninstalled apps.

[gadusmorhua]

My HTC Desire (running 2.2) shut itself down whilst sitting on its charging dock.It restarted itself immediately, but it had uninstalled several apps, all of which had been saved to SD, using the app Appps2SD, which was also uninstalled.I successfully re-installed all these apps (about seven), bar the London Underground app, which will not install to phone or card.
What is the likely cause of this odd behaviour- an automatic software update or something??