Visit the Dell support website and navigate until you find the Dell model#. Look at the bios level, if you need it, get it and update. The update *may* include handling larger HDs as the system becomes capable of such installs. I do suggest you install the old HD back in and check during the boot-up if you can launch your CD recovery disc. If not, be sure to check bios that the CD drive is the 1st boot-up device. If that works out and hopefully any bios update has been done, NOW install the new HD. Boot-up to use the recovery and see if that works now. If not, verify you have the HD jumper set correctly. READ THE MANUAL the for the new HD. If no manual, visit that HD maker support website for that HD model# and find it. If nothing works and all checks out proper for setup, then the laptop simply doesn't support that large of a HD install. It may support a larger HD but not a 500gb one, that's why you need to verify at Dell support. Sometimes checking the Dell upgrades if offered and/or any Dell compatible vendor website. This very much a laptop issue and the older the laptop the more likely the cause, of non-install.