I also can not get my windows disk defragmenter to run. I have run the disk error checking function in local disk properties and tools tab, which on reboot completed the chkdsk task before the windows screen came up without any apparent problems being found.
wheni i try and launch the disk defragmenter i get a dialogue box (see attachment).
i will download one of the alt defragmenters but would like to know why this has happened. I have recently had problems with an internet 2010 malware virus, when i had to make a recovery disk in order to restore my system and believe that this is probably the reason.