There are multiple reasons why your machine pulls up into "switch(boot)" mode.
I'm not sure what your setup is, but I have run into this issue myself when installing the N1000v directly on VMware Workstation. Make sure that you have set appropriate specs for your VM in whatever environment you are using. This message usually appears when the image file is not present on the supervisor. In this case, you could specify a .bin file for it to load. Check out these links for reference:
The PDF attachment helped resolve my issue.
Other helpful starting points:
Page 18:
http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus1000/sw/password_recovery/passwordrecovery_n1000v.pdf
Possible Upgrade problems:
http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus1000/sw/4_2_1_s_v_1_4_a/troubleshooting/configuration/guide/n1000v_trouble/n1000v_trouble_5upgrade.html
Link For installation on Workstation (or Fusion) on top of ESXi:
https://supportforums.cisco.com/document/144586/how-deploy-nexus-1000v-lab-vmware-workstation-or-fusion
