can not login as admin


i recently got my new dual G5 and transferred some files by connecting from my Cube via logging in through my router after logging in as admin on Cube so i could access all files...

all of a sudden today i can not log in to the Cube as admin nor connect as a registered user via my G5 with what i know is my correct login for admin??

can anyone give me some help to be able to fix the login problem??

Thanks a lot!!