try rebooting and clearing cache and try it. if that still doesn't work uninstall rom manager (if you have it, if not i would recommend downloading it because it is extremely useful) and then reinstall it and try to flash clockwork recovery again and then try making a nandroid recovery. good luck and let us know how it goes.
im going to move this to the droid hacking forum because it will be viewed by more people who might be able to help you further if it doesn't work. And this belongs there to begin with.