Hi s2smedia,
Basically you're hitting the memory and time limits that your server allows. Without modifying the code, one option would be to export fewer records at a time, perhaps by using the search fields to export all records that matched one criteria and then another export for records matching remaining criteria (eg: active vs archived users).
Depending on the server configuration, sometimes you can bypass some of the limits. If you want to try bypassing the max execution time you can add this to the plugin (csvExport.php) before the line that says "DON'T UPDATE ANYTHING BELOW THIS LINE":
// DON'T UPDATE ANYTHING BELOW THIS LINE
set_time_limit(60*2); // allow up to 2 minutes of execute time
Let me know if that works for you.
Dave Edis - Senior Developer
interactivetools.com