"Power Cycling" would just mean the phone turned off and back on. Which would be odd to have it do, unless there is something on the phone that is causing problems. Virus, malware, bad app, etc. However, if you say got an update to the OS then it could turn itself off and back on when it was done. That, however, shouldn't mess with access to the apps, even those on the card. Have you tried restarting (turning the phone off and back on) on your own to see if it will resolve the issue. Not restart, but power off and then turn it back on.