login problems for squash ladder member

One of the ladder members is having some problems logging in to our squash ladder site.

I've logged in as Administrator and tried to sort it out through the "manage players" page and here's what happens:
1) If I click on the player and ask to reset their password =
The password could not be reset - please try again later.

2) If I click on the player and ask for a player break =
Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /home/squashl/public_html/include/functions.php on line 468
Error

3) If I click on the player and ask to delete the player =
Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /home/squashl/public_html/include/functions.php on line 468
Error

4) If I try logging in as the player (using their email address) and use the password from the exported excel database =
You could not be logged in.
You must have entered the wrong email address and/or password.
Please go back and try again.

Please can you provide some advice.
Many thanks