People who have installed iTunes 7.4 and have tried to Jailbreak or use other software to mod have found that their iPhone is now a brick. The iPhone just goes into an infinite reboot.
If you are going to mod with the new iTunes, you have to use the new software that developers are relasing and not the old stuff. If you are going to mod with the old itunes still, stick with the old software.
If you have already bricked your iPhone here are the steps to fix it.
iTunes 7.4.2 endless reboot loop: Here is what you to do solve it:
1.) Make sure you have iTunes 7.4.2 intalled
2.) Make sure you have AppTapp 3.0 installed
3.) Make sure you kill iTunes and iTuneshelper using acitivity monitor
4.) Put your iPhone into recovery restore mode (yellow triangel) by holdning down sleep and home button together for about 25 seconds.
5.) Now start AppTapp, but do not click anything
6.) Open Terminal, cd to the AppTapp application, into Contents/Resources/
7.) now type ./iphonecomm -s 4
That’s it, you should be out of reboot loop, and you will be able to activate/jailbreaking using the AppTapp 3.0 application.
Win apps will very soon be updated too.