I am trying to load Windows 8.1 OS over my current Vista Home Premium. When 8.1 Cd is in and I restart computer to boot menu, I select CDROM but my computer starts up with Vista, it is not opening 8.1 CD. The CD opens in Vista, and my Office 365 opens in Vista so I don't think it is the CDROM. Could this be a boot menu issue, and can anyone help with it? Thanks in advance!
If it's a desktop, take off the side cover and disconnect the SATA lead for the HDD and then boot, if it doesn't you know it's probably your DVD. If it does, re-connect your SATA lead (You can do it with the machine running) and use Drive Options (Advanced) to delete all partitions on your HDD for a clean install to Unallocated Space. (Having backed up your data of course...)