Steps to Reproduce:

1. Create a VM.
2. Set boot sequence for the VM as follows:
  First Device: Hard Disk
  Second Device: [None]
3. Add network to the VM.
4. Run Once the VM. In the Run Once dialog select the following boot sequence:
  First Device: Network (PXE)
  Second Device: Hard Disk
5. The VM is booting from the network.
6. Shutdown the VM.
7. Remove the network from the VM and add it again.
8. Verify that VM boot sequence is still as described in step 2.
9. Run the VM.

Actual results:

The VM is booting from the network.

Expected results:

The VM is booting from the hard disk.