HELP, mac losing connection to shared folders on PC

I have a small workgroup set up at my office. The PC is Windows 7 & and the Macbook Pro is MAC OS X V 10.7.3.

The MAC keeps losing the connection to the shared folders on the PC and I can only restore the connection by rebooting both machines.

I have disabled Autodisconnect on the PC, added the MAC to the workgroup, etc.

I would greatly appreciate any help! Thanks!