Cisco Firewall :: ASA 5505 Disconnecting Inactive TCP Session?

My company has a DCS network that was previously segregated with a layer 3 switch and a handful of access lists.  However, there came this big push to segregate all DCS networks with Firewalls, so I purchased a 5505 and duplicated my simple access lists on the firewall and everything worked.  There is no NAT, just explicitly permitted traffic out and explicitly permitted traffic in.  However, there are some applications that connect and work fine for a few hours, then disconnect and the user must exit out of the application and go back into it, then it starts working again.  Previously with the Layer 3 Switch/access lists, this never happened.  Since I put the firewall in place, it has happened 3 to 4 times a day every day for the last week.