Start ->Programs -->Accesories --->Paint ---->File/OPEN ( select your photo ) ----->Image ( stretch/skew ) ------> chang the horizontal/vertical from 100% to 50% for both h & v. ------->File/Saveas Name.jpg
no worries, the problem is going to be the type of file you are trying to save... Repeat all of te above steps, and when you are saving your photo make select file the "SAVE AS TYPE" as a .JPEG - see below: