Are you running windows XP or Vista?

 

Try last known good configuration. These are the same steps for vista and xp. Shut down the computer, restart and keep tapping F8. Once at the windows advance boot  menu select last known good configuration.  This will restart the computer see if you get the same error.

 

If you are using XP i would try a system restore from the recovery console. Unfortunately you do need the windows XP cd for that. If you can't find it, usually if you can chat/phone tech support and they will get one out to you. 

 

 

Once you have booted to the XP cd, and are at the welcome to set up screen  hit R. log into windows installation. Usually its 1: c:\windows

 

At the Windows XP Recovery Console command prompt (C:\WINDOWS>), perform the following steps:

1. Type the following command:
   cd \
   There must be one space between cd and \.
2. Press the key to display a C:\> prompt.
3. Type the following command:
   cd system~1\_restore~1
   Note the underscore character after the backslash.

        An Access is denied message may appear.  If so, follow the steps below:

1. Type the following command:
   cd windows\system32\config
2. Press the key.
3. Type the following command:
   ren system system.bck
4. Press the key.
5. Type the following command:
   exit
6. Press the key.
   The system will restart.
7. Begin again with the first step under

1. Type the following command:
   dir
2. Press the key.
   Among other information, the dir command will list one or more directories, such as RP1, RP2, and RP3. These directories contain Windows XP Restore Point data.
   Make note of a recently created RP directory, but not one that was created in the past few minutes.
3. Type the following command:
   cd rp
   where equals the restore point data directory number (i.e. RP3) most of the time you would want to select the highest Restore point number.
4. Press the key.
5. Type the following command:
   cd snapshot
6. Press the key.
7. Now to recover the regestry type in the following commands pressing enter after each on

copy _registry_machine_system c:\windows\system32\config\system
copy _registry_machine_software c:\windows\system32\config\software
copy _registry_machine_sam c:\windows\system32\config\sam
copy _registry_machine_security c:\windows\system32\config\security

          If queried whether to replace the file, press the key and press the key.

1. Type the following command:
   exit
2. Press the key.
   The system will restart.
3. Remove the Windows XP CD from the drive as the system begins to restart.

If Vista, and you have not reinstall it. You should have the Windows recovery environment, as a option in the windows advance boot  menu(repair your computer) most dells do from the factory. Select repair your computer, log into the windows installation, again usually C: Then select system restore. Pick a date when you weren't getting the error. Once system restore is done it will restart your computer.