http://forums.macrumors.com/showthread.php?t=334220
There are some posts on this thread that can help you.
I'll try to give you the instructions but you can always fall back to it:
1. Disconnect the iPhone from the sync cable. (You may want to restart your computer before doing all this)
2. Hold the Sleep/Wake & Home Buttons down for about 30 seconds. You should see the iPhone reset then turn back on, then turn off again.
3. Turn the iPhone back on.
4. Hold down the Home button.
5. While holding down the Home button, connect the sync cable back to the iPhone (Make sure its connected to you computer and make sure iTunes is up and running).
6. Continue to hold down the home button until you see the restore message in iTunes.
7. Continue with the restore.
I had similar trouble except mine was with Scribble. Hope this helps.