Its a standard now to install OS using PD. So you haven't done any thing wrong to worry about. Ok try this :
Click the Windows "Start" button. Type "cmd" in the text box and press "Enter." The "cmd" word opens the windows command line on any Windows computer.
Type the following syntax in your command line prompt:
convert g: /fs:ntfs
This command converts the "G" drive to the NTFS file system.
Press "Enter" to run the conversion. Press "y" to confirm that you want to convert your file system. Conversion takes several minutes.
One more thing if you want to install OS using pen drive I can help you. Good luck.