What antivirus did you use before CAVS? Some are difficult to remove and leftover traces can cause problems with CAVS installation. I recently had a problem similar to yours which was caused by a Norton installation that had not uninstalled as it should have. Even Norton Removal tool did not solve this and I had to search for registry entries and folders and manually remove them.
Autoruns from sysinternals is a good program to help figure out what is starting up when you boot your pc and you can stop obsolete files from starting too.
Did you try installing CAVS in safe mode? This is a good method of installation as there are no conflicts with anything whilst the program is installing. Still got to ensure no remnants from previous antivirus/firewall installs prior to installing CAVS though.