The system cannot find the file specified

CIS Premium 5.3.176757.1236
GATEWAY PC
DX4831
WINDOWS 7 HOME PREMIUM
64-BIT OS
RAM 6.00 GB
HARD DRIVE 1TB

Hello everyone,
The updater box pops up regularly stating whatever database has been updated which is good. My system has been running extremely slow, so I thought I’d “Check for updates” and then do a full scan. When I clicked to check for updates, I received the message: “The system cannot find the file specified”. Yes I am logged on as administrator. Could this be why I have slowed? Do I need to re-install CIS? Thanks