unable to connect through ssh

Hi

i m currently unable to connect through ssh in my switch.

when i try to connect i got the following messages

Received disconnect from 172.16.8.52: 2: Connection closed by server: Server reached maximum number of simultaneous connections

Nevertheless when i connect through serial console 

show users

Username Protocol Location
--------------- ------------ -----------------------
Serial 0.0.0.0

there s no other user connected. 

How can i solve my problem without rebooting. i have some experiment running that require no network outage.