Except that it isn't that simple. Any program you add to Windows will raise the spectre of cross linkages in the registry. It isn't -supposed- to happen....but it does. There is also the possibility of dead COM linkages there that are being invoked. The fact that -removal- of P5 seems to somehow have disabled utterly unrelated OS maintenance software suggests to me that there is Evil Afoot in Registry Land (and the reboot was for the benefit of Interlok, not the actual P5 program, IIRC) whoopdat, have you run a registry cleaner lately, just to check for reg rubbish? And search your C: for interlok.exe; P5 1.0 installs it, and unless you deliberately removed it, it remained when you uninstalled it. Interlok is a commercial product that other apps use, and P5 couldn't uninstall it without breaking other applications.