Open Dental uses MySQL as a database. According to MySQL documentation

If you get the following error, it means that mysqld has received many connect requests from the host 'host_name' that have been interrupted in the middle: Host 'host_name' is blocked because of many connection errors. Unblock with 'mysqladmin flush-hosts' The number of interrupted connect requests permitted is determined by the value of the max_connect_errors system variable. After max_connect_errors failed requests, mysqld assumes that something is wrong (for example, that someone is trying to break in), and blocks the host from further connections until you execute a mysqladmin flush-hosts command or issue a FLUSH HOSTS statement. See Section 5.1.3, “Server System Variables”.

In other words, MySQL is banning a host for repeated connection failures. By default, MySQL blocks a host just after 10 connection errors. You can adjust the value by setting max_connect_errors to much higher value, say 4294967290. You can also invoke command 'flash hosts" that resets connection error counters.

To set max_connect_errors and/or issue 'flash hosts', login to the server and launch MySQL Command Client typically found under Start button/All Programs/MySQL/MySQL Server 5.5/MySQL 5.5 Client Command Client.

When asked for password, type the password and enter Return key. Note that typically the password is empty, so you hit Return key on the prompt. 

On mysql> prompt, enter SHOW GLOBAL VARIABLES like 'max_connect_errors'; and hit Return key to display current max_connect_errors value.

To change max_connect_errors, enter SET GLOBAL max_connect_errors=4294967290; on mysql> prompt and hit Return key. 

To reset error counter, enter FLUSH HOSTS; at mysql> prompt and hit Return key.

It always advisable to investigate why errors occurs in the first place. Please discuss this issue with practice IT department. 

Please note that YAPI PMSODBC app can be used to run above commands as well.