If you want to check if combo user/password is correct, you can do this by this command on Windows command line
runas /noprofile /user:DOMAIN\USER_NAME "notepad"DOMAIN and USER_NAME replace with correct Domain name and User name.
In next dialog you will be prompted to enter a password. If credentials are ok Notepad application will start in window.
On the other case you will get this error :
Enter the password for DOMAIN\USER_NAME:
Attempting to start notepad as user "DOMAIN\USER_NAME" ...
RUNAS ERROR: Unable to run - notepad
1326: The user name or password is incorrect.