Dell has some pretty decent onboard diagnostics to help narrow down potential problems.
I believe you can access it by pressing F12 for the one-time boot menu upon start up and then go to diagnostics. Let it do its thing and see what it finds to be the culprit.
Did this error happen after installing a certain application? If so, you can try to access the system recovery using the windows 7 disk and try a system restore to roll back to a date prior to this happening. Here is a guide to walk you through the steps.
If System restore doesn't work please choose Command Prompt. When command prompt opens type sfc /scannow to do a windows file check for any corrupted windows files.
*When opening the Recovery console, if you look up top it will say "Operating System: Windows 7 on (D:) Local Disk." Yours may be a different letter. The recovery console remaps the letters so C is actually D and vise versa.*
After doing the sfc /scannow please do a chkdsk /r for me using the same method that you did with the sfc /scannow. Type chkdsk /r D: and let it go through all the stages *There are 5 stages.*
Once again your drive letter may be different. If it is simply replace D: with your drive letter.
Let us know the outcome please.
Edited by chrisd87, 17 October 2013 - 11:28 AM.