login won't work for Internet Explorer

Hi there, I am experiencing a peculiar problem. I have recently moved a PHP / MySQL driven website I have been developing from my linux box on to a live host. Everything seemed to go smoothly apart from one peculiar problem. When I access the site using Internet Explorer (so far I have tried 5.0 and 5.5), I am unable to log into the members' section of the site. Instead I receive the following error: Warning: Unable to jump to row 0 on MySQL result index 2 in [pathdir]/member_login_check.php on line 12 Warning: Unable to jump to row 0 on MySQL result index 2 in [pathdir]/member_login_check.php on line 13 Warning: Unable to jump to row 0 on MySQL result index 2 in [pathdir]/member_login_check.php on line 14 The peculiarity is that when I log in using Mozilla, I have no problem. Why should the choice of browser have any effect on a set of processes which are all server-side? Or am I completely wrong about that? All suggestions and help appreciated. Thanks, Ben