Corrupt 12.04 automatic update

[Joe Bissett]

After all of my problems with the corrupt automatic 12.04 download, I am 
finally able to access 12.04, but not as the primary user 
(administrator), only as Guest.

i am unable to sign in to my administrator account.  This is very 
confusing.  I can not enter my password in the login prompt when 12.04 
first comes up.  As soon as I put the cursor in the login space and 
release it, the software recycles back to the login prompt.  I tried 
Recovery Mode, Ubuntu, Ubuntu 2d and Other, but the same recycle takes 
place immediately.

However, I can get into 12.04 with Guest, and then using the icon at the 
top right I can look at my Administrator account.  The password there 
says None, but I actually do have a password, and I have not changed it 
since version 7.

I know the password is still recognized "somewhere" in the op system, 
because I have a direct link from my Windows XP to a file folder called 
"Test" on the Ubuntu machine.  To open the link requires entering my 
password.  I can open the Test folder over the link using my correct 
password, and I can copy files back and forth.

Does anyone have any ideas?  I am a total newbie, and I am very frustrated.

Thanks in advance.

Joe Bissett