It will be very handy to have an uninstalation utility that will delete all the settings and everything that has to do anything with ArcGIS Server, so that you can do a fresh install. Lately i been getting lot of errors with All instances of arcgis server failed on host machine but i cant find a way to find out what is causing this. i beleive, if i uninstall, and then do a fresh install, will probably solve this issue..
