The problem isn't with cleanmem, it is something with the task scheduler. Did you try deleting the schedule and remaking it?
Cleanmem runs on over 1 million machines, from every version of Windows from xp to 8 and all servers. The error is coming from the task scheduler not cleanmem. A lot of times when ever I have trouble with a task scheduler I just need to delete the task. On some other machines there was a security issues with it and I found a fix for that and that got task scheduler working. But that error kept every task in the task scheduler from working

Also on a side note, alot of the other memory cleaners out there simply copied what cleanmem does with the API. But they dont do something else that I do, you will see Cleanmem can clean out of more processes then they can

Anyways, need anything else let me know.
Shane