Well, I found something that seems to work, although it's not a solution for everyone unless they have an MSDN subscription or an extra Windows license at their disposal, a relatively fast machine, and enough available memory.
My issue was strictly with a LaunchPad - no FET was involved. After setting a fixed com port for the device, I still was experiencing the same problems, and couldn't find any other process on the system that was using the device. So, I fired up VirtualBox and ran a Win7 virtual machine with the TI device captured to the VM. After unplugging and plugging in the LaunchPad, I found that CCS (running on the Win7 VM) can reliably talk to the LaunchPad and I can load and debug code on the MSP430. In a similar manner I can route the LaunchPad device to a Linux VM and load and debug code using Eclipse, the mspgcc toolchain, and MSPDebug (since the LaunchPad is not supported in CCS under Linux). Debugging is sketchy though, as the MSP port of gdb has problems correctly associating variables with the proper memory locations and thus often displays incorrect values for those variables.
So, for the time being, I guess I will be using CCS in a VM. Based on the advice of another poster, I ordered a separate Via-based USB card to see if that will allow me to run CCS natively on the Win8 host machine. I'll let everyone know how that works out.
Thanks again for your time and assistance Jens-Michael. It's very much appreciated.