sounds like your BIOS is corrupt, and it should be an easy fix.
When it it first turning on with the Dell logo press F2 to get into BIOS (Blue screen with white and gray text).
Go down to "Maintenance", enter, down to "Load Defaults", enter, right to select "Continue", enter.
Then go up to "Power Management" and check "USB Wake Support" and "Wake on Lan/WLAN" and make sure both are set to 'off'
Lastly go up to "System" and "Date/Time" and make sure that the date and time are correct.
Press "Esc" and then select "Save/Exit" and see if that fixed your problem.