Danny, the Flash_Disinfector does not require installation on your computer. Simply run it. Once started, it creates a hidden folder, named autorun.inf on your Usb drive to protect it from autorun trojans.
I noticed that my computer is now using up an awfully high amount of Hard Drive memory
Probably your computer is infected with a trojan or virus. Check your PC system with the following free tools:
MalwareBytes Anti-Malware from http://www.myantispyware.com/download/malwarebytes-anti-malware
Kaspersky virus removal tool http://www.myantispyware.com/download/kaspersky-virus-removal-tool