Passwords suddenly not working

PHP List, I have a few scripts that have been around for a while. In one, is a simple login function: $query = "SELECT * FROM forum_members WHERE memberName = '" . $username . "' AND passwd = MD5('" . $password . "')"; $result = mysql_query($query); This was working fine, but recently I haven't been able to log in. I think the only thing that has changed is that on my hosting service, they recently upgraded to PHP 5.1.6. (MySQL is 4.1.21, but I think it's been that for quite a while) Is there any potential for PHP 5.1.6 to handle things different when it comes to MySQL queries, post data, or anything? I thought it might be that I still had $HTTP_POST_VARS for some of my variables, but I changed them all to $_POST, and it still doesn't work. I don't get any errors or anything. My own code is not very sophisticated for error reporting. But I'm not getting any PHP syntax errors of any kind. If I run the SQL code by itself at an SQL command prompt, I get results back, so I don't think the SQL is failing. Are there any gotchas in the upgrade that I might be missing? I can't think of anything else that could be a culprit (though of course I'm open to suggestions). Any advice would be much appreciated. -- Dave M G Ubuntu 6.06 LTS Kernel 2.6.17.7 Pentium D Dual Core Processor PHP 5, MySQL 5, Apache 2