It very much looks like a re-install may be necessary.
If you are thinking about a re-install and don't have a disk then doesn't your dell PC have a Dell System Recovery - extracted this from a blog:-
Performing a recovery returns the computer to its original condition. It removes all software and files saved to the hard drive, reinstalls the original operating system, and then runs an initial setup to install the default programs. For best results, the computer should be connected to the internet, and it will restart several times during the process. Do not turn off the power or interrupt the recovery process until the Windows desktop appears.
How to access Dell System Recovery Partition :
Press the Power button to start the PC At the Dell logo, hold the Ctrl key and press the F11 key simultaneously. The Dell PC Restore screen will come up. Select Restore or use the Tab key to highlight it and press
Enter. if you wish to continue, click Confirm, or use the Tab key to highlight it and press Enter. When the utility is finished, click Finish, or use the Tab key to highlight it and press Enter.
WARNING: Because the recovery process deletes all the existing files and programs, we recommend that you do the following actions before doing a system recovery:
Perform all of the other troubleshooting options to return the computer to the proper
operating condition. Perform a complete backup of all important data and files.