I currently have Spybot S & D, Ad-Aware SE and Microsoft Antispyware Beta all loaded on my p.c. (and use them regularly). I also know of many others who are in this position and with no problems. There is no reason whatsoever for the programs to clash under normal circumstances. If you have a problem I'd suggest that another factor is involved that you may not be aware of. The only one of the above which is a running item is the MS application. The other two are ad hoc scanners. Maybe someone else will come up with a useful suggestion, but my initial reaction is that we are missing a vital piece of the jigsaw.