1. Restart the computer. Press <F12> immediately after the DELL™ logo appears.
2. When the boot device list appears, highlight CD/DVD/CD-RW Drive and press <Enter>. This changes the boot sequence for one time only. On the next start-up, the computer boots according to the devices specified in the system setup program.
3. Press any key to Boot from CD-ROM.
4. Do a Startup Repair - see
http://www.vistax64.com/tutorials/194765-system-recovery-options.html Method Two. When it shows the list of operating systems installed, select the one on your D: drive (if they have identical names, select the second one).
Then, click on Startup Repair, and follow any instructions. If it doesn't fix anything, Restart and go back to Step 1, but this time select the OS on Drive C:
Let us know what happens.
Ed