In order to fix this issue, go to Start, type msconfig and open the application. Press the Startup tab, un-check the box next to Dell Support Center, click Apply, reboot the PC and try again. If doesn't work, I suggest you upgrade the application manually.
If you use Windows XP or below you can go to Start > Control Panel > Add or Remove Programs. In the Currently installed programs box, click on the Dell Support Center program and then click Remove.
If you have Windows Vista or above you need to go to Start > Control Panel > Programs > Programs and Features. Select the Dell Support Center application and click on Uninstall.
If doesn't work, try using Revo Uninstaller. Even if it can't uninstall the application normally, it will force it to uninstall by wiping out all traces of its presence from the system.
After the removing process is finished, download the latest version of the software and install it following the provided instructions. Make sure that you're logged on an Administrator account when you install the program.