it a bad bug with windows. with sata ports and hard drives now if your not carfull in the install of windows now it will blow away a drive partion info to set up two new partions...a system partion and a active boot partion. the missing drive just needs to be formatted using windows disk managment if the partion has not be tuched by windows install. then it will be given a drive letter and should be seen in windows fine. to fix the other drive your going to have to redo windows install. or use windows drive tools to resize the partions. most times with more then one drive i tell people to unplug the data cables of the drives they want windows not to tuch. makes for an easer install.