i have a dell inspiron 1545 and for some reason my ac adapter won't charge. The little light wont turn green. I replaced my first adapter but then it happened again to my second one. Also my laptop is new, I have only used it for a 5 months and I dont download anything on it, I simply use the microsoft applications and do database researching from secure universities website. does the problem have to with my computer? What can I do to fix it?