I recently added a new hard disc to my pc. Old one is 500G and new one is 1 Terrabyte. If i open the device menu, it shows the new device, but after a while it disappears from the menu. I had a 2nd opinion about the installation and that is not the problem. Any help?When you say "device menu" are you talking about device manager? Does the drive show up in Windows Explorer? How about in disc MANAGEMENT? Did you format the drive?If you click on start and then devices and printers, under devices it shows and then goes away, it does return but not for long before it disappears again. I am not sure what windows explores is. Also if i click the `my computer` icon it shows the old HD and the DVD rom, and the new HD does the same there, APPEARING and disappearing. When i installed the device windows asked me to format the drive before i could USE it, which i did.Why are you even looking in Devices and Printers?

Windows Explorer is the file manager. Go to START - RUN and type explorer.exe then press ENTER. Do you SEE the new drive? If so, you're fine. If not, go to START - RUN and type diskmgmt.msc and press ENTER. Do you see the drive there? If so, what does it say?