The other day I tried to get my MSP8 to run and it absolutely refused. I did all the normal things like uninstall, re-install, uninstall for clean install, applied the patches with several reboots thrown in. Nothing worked.
I then fired up my trusty "Process Explorer" by Mark Russinovich of Microsoft (http://www.microsoft.com/technet/sysint ... fault.mspx) and started killing of processes. This usually doesn't work for me but this time it did! The culprit? "ReplayAV" from "Applian" -- I use it to d/l podcasts and record internet radio.
Anyway my point is that if I had done this FIRST
I could have saved myself a whole lot of aggrevation. Now I know to unload ReplayAV before I launch MSP8 and life is good again 
BTW... the link above is to a bunch of free (yes free from Microsoft) very good utilites.
I hope this info helps those having trouble getting MSP8 to launch.
Cheers,