SemiTether has been updated to fix some issues.
“I updated to 0.7.9. This version will take about 90 seconds after it first boots up and then your device will respring again. This timing was the only way to get some of the launch daemons to properly relaunch.”
SemiTether 0.7.9 should fix issues for some of you where:
1) Device does not sync with itunes and only errors. Hopefully solved.
2) Device reboots after 2-3 minutes.
Here is a video guide: