The hard drive in question was one that originally came inside of an acer laptop that died recently, to keep the data and also make use of the 600gb HD which seemed to be working fine I got an external HD case and used it from my desktop PC via USB. Everything was fine until today while editing some photos which were on the drive I got an error that the drive was unavailable. It then automatically tried to reconnect but windows 7 told me that there was an unrecognized USB device trying to connect and that it couldn't install the drivers. I unplugged and replugged a few times then I got the error that the drive needs to be formatted before use (I now start to freak the hell out). I also tried plugging the USB into my laptop, the lights came on but nothing happened, no message at all in windows. As a last option I decided to try taking the HD out and switching it with the one inside my Toshiba laptop, turned the laptop on and somehow it managed to boot up the old windows installation which was on it and seems to be working fine, all files working.
Does anyone know what could have happened here? I am currently making an exact backup of the drive and a bit scared to put it back in the USB case till I at least have that. Maybe the USB case has the problem? I also noticed windows tells me the drive has errors and wants to scan it when I plug it in over the last several days, but I get that message on a lot of stuff so just ignored it.