Cursor freezed when opening a folder containing many video files

windows 7 Ultimate with SP1
COMODO TIME MACHINE
CIS FREE 5.4
Everytime I open a folder containing many video files and drag the cursor to some place, the cursor stops at somewhere and jumps to another place, at the same time, a thread called “dllhost” shows in the taskmgr and takes as much as 50 percent CPU usage, what’s up?
Is this caused by CIS or by my windows settings? Thanks

Herro;

Do you have any other Security Applications Running at the time of the occurring?

Also; is this dllhost.exe?

Yes, it’s dllhost.exe
I just installed CIS Premium with av on and defense+ in paranoid mode
PS: Sorry for the late reply…Still not familiar with the forum’s noticing system