Please open your Device Manager. Start > right click > computer > properties > device manager. Does it look like the following, are there any devices marked with an error? What drivers have you installed? [IMAGE] 
Having used the disk provided for "Re-installing Dell XPS 8300" I proceeded to download Drivers and Utilities. I used the advice " A hardware scan has detected the presence of this device" and successfully downloaded all the drivers except "Intel Sandy Bridge Graphics Rev AOO" which gave the error message "This computer does not meet the requirements for installing the software" As it was detected and initially allowed me to download and extract the file this does not make sense. The system is as originally provided 6 months ago except RAM increased to 12gb. CPU i7 2600, Windows 7 Home Premium 64bit, SP1,   Any help please?
Re-installation of operating system/drivers and utilities