Today, I decided to update the firmware on my iPhone 3GS to 4.2.1, then jailbreak using Redsnow. This worked perfectly fine and I then proceeded to reinstall apps in Cydia. Something required a reboot, and then it got stuck on the apple logo screen for half an hour. I am able to get past this by using 'boot tethered' option in redsnow while it is on the apple logo screen, but every time I need to reboot the device, or switch it on/off, it gets stuck again. Its obviously not practical to have to use the boot tethered everytime I need to switch on my iPhone, so I need help on how to fix this Thanks in advance!