I take it that it has happened more then once?
First thing I would do is test the hard drive for errors, if it's the original Dell drive and has not been formatted it'll have a Diagnostic Partition.
What Model Dell?
The alternative is to find the brand of the drive manually to to so > Hit Start in the search box type/paste devmgmt.msc and press Enter. Click on the + sign next to Disk Drives copy the info listed and post back.