As you weren't very specific about which method it was you used, I'll explain what I did because it worked for me.
i used this method to install Lion, and when updated to 10.7.2 i have gray screen and spinning wheel at boot. I replaced boot file on the thumb drive and reinstalled Lion again, updated to 10.7.2, it only boots up if i boot from the thumb drive, if i boot from HDD it hangs again, where did i go wrong?
- download 10.7.2 combo updater from Apple
- download Chameleon Wizard, and then install latest version of Chameleon (v1618 was the one I used.)
- download boot_for_10.7.2_and_icloud.zip and copy the boot file into your HD's root directory (the one with Users, Extras, Applications, System, etc.)
- open Terminal and issue this command "sudo chmod 755 /boot"
- then this one "sudo chown root:wheel /boot"
- next, either dl & open KextWizard; repair permissions and rebuild caches (or search for the Terminal commands to do so)
- then copy AppleHDA.kext (assuming you have audio working) and anything else that you've added to S/L/E to desktop for post-installation
- Finally, apply 10.7.2 update, reboot, pray to <DEITY HERE>
alternatively, you could enter verbose mode (down arrow key when it shows the HD on GUI boot) and jot down the offending kext.
running 10.7.2 very nicely on ud3l/e8400