I got an issue during Joomla 1.5 work .
Not able to login in backend admin area with correct login details..
I solved it by below method….
In phpmyadmin database area, go to the table jos_plugins (jos_ will change depends on your table prefix).
Then check the table field name with value User – Joomla .
Click on the Edit icon
Go to the area where it says published and change that from 0 to 1
And I can fixed my issue…
Hope it will help some…