When the phone first boots, only the apps installed in phone memory appear. It takes a while to scan the SD card and find apps there. While that scan is running you will see an icon with a micro sd card and a settings gear in the notification area. When it's done, your apps will appear. If your external SD card is huge this could all taker a while. If you are impatient and start tapping on your icons you will get application not installed messages. Suggestion: watch your home screen until the sd/gear icon drops off the notification area and the app shortcuts on your home page turn into the correct icons. Then try your apps. Any app that totally has to be running right after a reboot, move it to phone storage if you can spare the room. And rebooting again is guaranteed to slow it down.