More than 10 SSH logons

I'm having a problem that is driving me nuts trying to solve. I've googled until my eyes hurt. Any ideas on solving this would be greatly appreciated.

I have about 20 users who need to logon to the same system (Slackware 10.2) under the same account. After 10 are logged on, the system will not accept any further remote logons for any username.

I've gone over my sshd_config with a fine tooth comb and made sure the kernel allows 256 logons for pty. I could have missed something with either configuration but I don't think so.

Please post even if you're just taking a stab at it and not sure. I'm willing to take a look at anything. Save my sanity please!

It may or may not help, but look at MaxStartups. That is defaulted to 10.

Can you post your config here?