Locked out of windows

I am on deployment with my laptop that has windows vista. I bought the
laptop while home on 2 week leave and have not had it long. Upon buying the
computer, I reset the administrator password, so there was not one. Upon
logging in, I always hit enter w/o entering anything and get into windows. I
shut down the computer last night and when I restarted this morning, I
discovered that windows is acting like I have a logon password. I do not. I
can not log into windows. When entering safe mode, I reach the same problem:
I am brought to the windows logon page, and can not get in as I get the error
stating "that is an incorrect password" or similar.
I would welcome any help or advice, as re-installing windows is not a
pleasant thought. I do not have access to blank cd's at my current location
in order to make the boot cd in order to reset a password, which is why i
have not done so yet.