So this is very odd.
Last night my phone rebooted itself. Nothing unusual there - it does it from time to time. However, this morning when I try to read the news I get
"Application is not installed on your phone".
So I check some more apps and lo and behold I get the same message. Any app that was installed on my SD card has gone - but only partially. The icon still exists on the "desktop" and the system name appears on the list of installed apps on the phone, but the Google Play store doesn't think they're installed - which is different to the symptoms described in these questions:
which both state that the applications are still listed as installed in the Play Store.
Also - now I think about this a few apps had gone missing earlier. I have gaps in the icon field where I know there was an application, but because I didn't use it everyday I can't remember which ones :).
I've tried removing and reinserting the SD card, but that's had no effect.
When I reinstall applications that have local data and/or stored account details this information is still present. For example when I opened the Amazon MP3 player it didn't prompt me for my Amazon account details, but just showed the list of albums I've purchased. This implies that it's just the folder that hold the executables on the SD card that's been deleted/corrupted.
I've started reinstalling apps, but I'm concerned that this might happen again.
So does anyone have any ideas why this might be the case?