Please try the below steps before installing McAfee programs ;
Click on Start – Click on Start search and type : cmd
From the option that pops up, right click on CMD and select Run as Administrator
In the command prompt , type the following and hit enter:
Regsvr32 jscript.dll and press enter
Regsvr32 vbscript.dll and press enter
Now close all the windows and run McAfee preinstall tool from here : http://download.mcafee.com/products/licensed/cust_support_patches/McPreInstall.e xe
Restart the PC and retry installation , if you still encounter the same error, please uninstall Internet explorer 9 [If you have it installed]
And try installing the programs on IE 8
The above steps helped in no way..i think there is a problem with the registry so i've formatted my pc and loaded new OS.
Then i tried installing McAfee and it worked fine...anyways thanks for your help.