Uninstalling Defraggler

I have been having serious problems with the computer since I installed periform defraggler....Now... I cannot uninstall it... when I go all programs and click on uninstall(to the Defraggler), this message shows up:

"Windows cannot acces the specified device, path, or file. You may not have the appropriate permissions to access the item"

Any idea as to what I am doing wrong? How can I uninstall this program... I tried using it but t no avail.. Yesterday, I left it on defrag all day and although it was working, it did no finish by the end of the day so I left it on all night and by his morning, only a little more had been done(whaever it was doing to defrag).

Have you tried to uninstall it in safe mode?

Make sure you close defraggler down first.