Cisco :: ASA 5505 Introducing Networking Loops

Have a number of organisations that I work with who are currently all changing their ISP to a different one. The company who are supporting this are introducing a new router and firewall to the network and removing the old layer 3 switch. Firewalling and filtering was previously done off site but will now be handled by the ASA 5505. I personally do not have permission to configure the ASA (nor would I know how to) So these places are set up with 2 ip ranges, so int 0 on the ASA is 10.0.0.1, int 1 is 10.0.1.1. The Cisco ASA has been configured with the same settings on it's required ports as the old layer 3 switch had, so nothing much has to change on the internal network. Problem is that the old layer 3 switch must have only been passing data through at layer 3, so basically not switching and not creating networking loops. It seems that due to certain required network topologies, switch A is connected to switch B, which is connected to switch C, which is connected to the ASA, but switch A will also be plugged into one of the interfaces on the ASA (creating a loop). As I've said, this was not a problem with the layer 3 switch but now the ASA must be switching at layer 2 (I guess...?) as well as routing to the internet (which is required for both ports, which are vlans) and so is messing up the lan with a switching loop.

can the ASA 5505 be configured so as to allow access to the internet for both vlans/ip ranges while also preventing switching loops being created? It seems definite that this is being caused by the introduction of the 5505 as the old setup was exactly the same, it's just that the 2 cables have been plugged into the 5505. We do not have the option of using STP here as the rest of the switches on the network are unmanaged.