Assuming this is a proper dns setup where all the workstation point to the server for dns and the dns server has the isp dns servers listed in the forwarders tab, I would suspect tha ASA is the problem.
But you have network drives disconnecting which is solely a server/lan issue and has nothing to do with the firewall since this connection to the drives never goes thru the firewall.
Lets start with a ipconfig /all from the server and one of the workstations losing the network drives for review.
But you have network drives disconnecting which is solely a server/lan issue and has nothing to do with the firewall since this connection to the drives never goes thru the firewall.
Lets start with a ipconfig /all from the server and one of the workstations losing the network drives for review.