Slow boot and shutdown with cis 3.5

From what I saw from a quick search is that avast might conflict with cis 3.0, however I do not use avast on my vista machine.
What else can cause the boot and shutdown to be extended with several minutes if cis is installed? (if uninstalled the boot-times are normal)
I downloaded cis 64-bit and I’m using vista 64 ultimate.
Also having a dualboot with win xp (64bit) although I have installed an older/different version there.

Due to not having a virus scanner yet under vista made me choose for this cis product, and having no problems with other comodo products helped also.