From: DeskNow Knowledge Base
http://www.desknow.com/kb/

I get this error when trying to login: "Too many failed logins from your IP address. Please retry later"
http://www.desknow.com/kb/idx/13/174/article/

This error can occur if you have enabled the security feature that prevents brute force password attacks, and DeskNow has received too many failed login attempts from your IP address. It will reject any login attempt (even if using the correct password) from your IP address for the amount of time that was specified in the configuration.

You can try and login from a different IP address to bypass the problem. Note that if you are connecting to your DeskNow server via a router using NAT, all the computers in your LAN will have the same public IP address, and will be affected by the same restriction.

You can change the settings by logging in as admin and going to Administration/Security/Authentication/Prevent brute force password attacks