I bought a Dell Inspiron N5110 for my granddaughter for college.  Her virus protection software didn't protect her from a virus that was running amok on campus.  She took the laptop to the campus IT department.  They cleared the virus, but while they were at it, they installed a different version of Windows 7 (Professional instead of Home Premier). The activation key shown in the system security window does not actiate -- "This is not a Professional Activation Key". A notice pops up saying that it must be activated in the next two weeks.  I have no idea how to get back to the original OS, since Windows 7 was pre-loaded and came with no discs.  Dell has been absolutely no help.  Any suggestions?  I hate to have to buy Windows 7, again.  The same thing happened with Office 2010 (or 2012, which ever was installed initially) except the campus IT did not even try to re-install that.