i had some issues with the temp root on z4 as well. i found that the best way to get it to work again (i had it working, rebooted my phone, and then it wouldn't root anymore) was to uninstall everything (i had superuser, z4root, titanium backup, and root checker installed)
here is my exact process for getting it to work:
1.) go into settings>apps>manage apps
2.) select titanium back up, clear data
3.) repeat step 2 for any other root apps that you installed (for me this was root checker, superuser, and z4root)
4.) reboot phone by pulling battery and leaving it out for 30 seconds
5.) once phone reboots go to settings>apps>manage apps
6.) uninstall all the root apps (again, for me this was z4root, superuser, titanium, root checker)
7.) repeat step 4
8.) after the phone reboots, leave it sitting on the table for 5 minutes, just to let everything settle.
9.) then i used astro file manager (this is an app that you can download from the market.. it allows you to manage files and folders on the phone/sdcard) to check for any files and folders related to the 4 root programs. i deleted anything i found related to these programs.
10.) repeat step 4 again...
11.) once phone reboots let it settle for a few minutes. download z4root and open it BUT DO NOT run it yet.
12.) go to the market place. download root checker
13.) go back and open z4root again, run the temporary root function. once it finishes use root checker to see if it worked. if it didn't work go back to z4root and run the temporary root option again. check with root checker... you get the idea. if it doesn't work within 5 tries, reboot the phone, once it has settled again try the temp root again and check with root checker. (i only had to temp root it 3 times before root checker told me that i had root access)
14.) once you get root access download titanium back up (or whatever other root apps you want to use).
15.) start using the root functions!
i know the process is a little drawn out, and i dont really have any basis for how it works aside from the fact that i figured that clearing out all the files would get it to work again... and for me thats exactly what happened. I've got titanium to work, as well as setcpu. (thats all i really tried.. superuser works as well)
I've made full backups using titanium, and i plan on going full root sometime within the next week so i dont have to worry about reboots and then not having temp root working anymore.
hope that helps some of you
And, if you are trying to attain full root, what program are you using?
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