System restore is probably set to D: drive. You need to purge all those restore points - on D: drive, right click > Properties > Disk Cleanup > More Options tab, then click under System Restore option Cleanup > Delete.
Then check if System Restore is active for D: in Advanced System Properties -click Start orb > right click Computer and choose Properties > in left pane click Advanced system Settings > System Protection tab and make sure D is not checked, if it is uncheck it and click Apply.
Also, if you use windows backup, check the backup parameters to ensure the images are not saved to D:.
Its possible the recovery partition is trashed, hope you made recovery disks beforehand. In any case you can always order recovery disks from dell if things dont work out.