Presumably you're using Win7 or Vista
This problem always appears as the Administrator account is disabled by default and so never set up, therefore no password - and you can't log into it
However it appears first in the list of logins when you try to access the recovery console
If you look again, you'll see that its actually a drop-down list of accounts - simply go down the list to find your normal user account and log into that
The fix that GG refers to above really only applied to early versions of XP which were preinstalled by large scale manufacturers - and all had the same security SIDs. It also affected the ability to login with remote desktop / remote help.. I can remember actually finding the problem and personally discovering that fix during checks of trial builds during a training session for our call centre staff! We reported it back to Microsoft, but doubtless others also discovered it independently.