windows vista ultimate

Dell xps/Dimension 9200 new march

 

since a couple of weeks or so  when i go to control panel then turn windows features on or off, the box comes up but it is completely empty

 

anybody know what to do

 

i googled and tried suggestions such as do a start up repair,no good.

tried sfc/ scannow

also restored to earlier time

 

nothing works

 

anybody any ideas other than to do a full system reinstallation to the day i got it from dell by using the dell disc image.

i dont want really to lose everything i have

 

any help appreciated