Cannot add more than 990 users

I’m trying to convert a few thousand users into a new WP install. The import goes well, no errors, tables look fine. But if I add more than about 950 users the user management page craps out, leaving me unable to even see users, or manage them.

I have to assume there’s not a limit like that, anyone have an idea what could be an issue here?

No errors in the logs, just a zero byte page back if I try to go to the authors and users page. I can edit the admin account just fine.

I’ve tried two methods of import. Direct sql with a conversion from the old, And using the plugin here:

http://www.dagondesign.com/files/dd-import-users.txt

Neither way shows errors on import. Nothing in logs, the wp_users and usermeta tables appear to be fine, just large.

Running on debian, mysql5, apache2, php5. Very standard install. Dedicated box to this task only.

Ideas VERY welcome. 🙂

Matt