Both Python and pywin32 are required for VANET simulations to happen successfully. This is essential for interfacing NetSim with SUMO which is a python based road traffic simulator. 

Check if Python 2.7 pywin32-220 is installed in your PC from the control panel. If not installed, download and manually install it from the following links based on the system configuration:

Python 2.7 pywin32-220 32bit:
Python 2.7 pywin32-220 64bit:

This should help in solving the issue.

Note: It is always recommended to run VANET simulations in Admin mode, preferably under the Administrator user account.