choppy/hesitating PC

The last few weeks my computer is hesitating and losing time when it does. I ran all my stuff, ie defrag etc. It seems to be worse when I run internet explorer and in a two hour sesson, my clock loses time. Do I have a bad program somewhere. I havent downloaded anything and my virus scan is working and i have no bugs. What is qttask?? Sometimes I close it and that helps. But not always

Should I run something with the disks I have from you???

Help!!!!!!!