Errors in our Firewall logs for UDP port 137 SMP 7.5

Hello All,

Our network admin sent me a question on what was trying to attempt to connect on UDP port 137.  We are seeing the servers try to communicate with the clients on this port about every 1 to 2 minutes.  This is filling up our logs.  Has anyone seen this or does anyone know what would cause this?

This is the entry in the firewall logs:

Apr 2 14:51:34 192.168.0.1 %ASA-4-106023: Deny udp src dmz:192.168.6.75/137 dst outside:209.121.225.244/137 by access-group "dmz2in" [0x0, 0x0]

My Environment:

1 Notification server

2 Gateway Server - In DMZ

2 site servers

All of my users are Cloud Enabled and only connect via the cloud.  We do not have any internal connections other than our test machines.  Any help would be greatly appreciated.

Thanks