Issue with installation of postgresql server

I have been trying to install Postgresql server on my machine (Windows 8-64 bit version) but it is failing to install by throwing the following error -
"There has been an error. The environment variable COMSPEC does not seem to point to the cmd.exe or there is a trailing semicolon present. Please fix this variable and restart installation ."

I searched some of the forums where the solution mentioned was to add an environment variable "COMSPEC" with the value - "C:\Windows\system32\cmd.exe". I did this but the issue persists. Also, there is no semicolon at the end in the value of COMSPEC variable.

I tried installing 2 versions of Postgresql but I am getting the same error for both. The versions are as follows :

1. postgresql-9.3.14-2-windows-x64.exe

2. postgresql-9.6.0-1-windows-x64.exe

Since the COMSPEC variable is present, it got me thinking if this is a general exception thrown while installing postgresql.
Also, are there any pre-conditions to be checked before installing the server. Could a particular software installation be hindering the postgresql installation (At some forums, it was suggested that the anti-virus uninstallation solved the issue. Could this be the reason?)

Please let me know how to resolve this.

Thanks & Regards
Kanakaraju

This message (including any attachments) contains confidential information intended for a specific individual and purpose, and is protected by law. If you are not the intended recipient, you should delete this message and any disclosure, copying, or distribution of this message, or the taking of any action based on it, by you is strictly prohibited.

v.E.1