Dell Inspiron One 2320 issue

My Dell Inspiron One 2320 has been a decent machine for nearly three years -- until today. After running without any issues for a long time, it suddenly operates very slowly. Ran AVG and and two anti-malware programs and they did not detect anything. Any thoughts on what could be causing this? His computer has been pretty exceptional and then, boom, all of a sudden, it operates at a snail's pace. Would appreciate and guidance this group may have to offer. Could this be a hardware issue? Thanks...