I purchased a 500GB Seagate External HD over a year ago and used it with my Windows laptop, and then with my Mac Mini and Macbook (after I came to my senses). However in this time I partitioned it to use it as a storage and backup. The problem is that the total capacity is now at 372.6 GB, nowhere close to the ~480GB capacity that it used to have. Is there anyway to recover the lost space or is it just due to age and over-formatting? Thanks!