MRU Blaster time settings?

I have only just realised that I can no longer change to timer settings for MRU Blaster I was able to do this pre-SP2 but have tried to adjust from the 15 min setting and there is no way at all for me to change this now. I have tried several times to adjust this setting but it is stuck at 15 mins. I don't mind if this is meant to be but just wondered why I could no longer select the time between scans.

One other question - If I don't have MRU Blaster running at startup will it only clean when I manually scan and clean? I have noticed that when I use 'regedit' for example and re-boot - regedit is in my Start - Run when I have booted again plus a lot of MRU's when I click scan. Do I have to let the icon run silently in my system tray in order for it to clean without asking? I hope his makes sense as previously MRU Blaster worked without me asking