I believe you must wipe data/factory reset if you are going from v1.5 to v1.6 or v1.7. If you wiped data/factory reset before going to v1.6 you just have to wipe cache, wipe dalvik, and format /system to go to v1.7. If you are going directly from v1.5 or earlier to v1.7 you have to do the wipe data/factory reset. You cannot get to v1.7 successfully unless you have wiped data before the v1.6 or v1.7 install. People who did not wipe data somewhere along the way are the ones having problems.