I purchased an Acer Aspire E5-575G a little over a year ago and have been using it without a hitch ever since. However I recently noticed I am short on Hard Drive space and when I went into My Computer to look, it shows my (C: ) drive as having 50gb free of 120g, and my (D: ) drive labeled "Backup" has over 900gb free of 979gb. There is no way this laptop came with a 100gb hard drive... why is my backup almost a terabyte and completely unused? Is there any way to take advantage of the almost 1 Terabyte of free space on the D drive or do I now need to buy an external hard drive? Any help would be appreciated, thanks.