I have a pretty decent laptop that's only a year and a half old. 2.9GHZ, 8GB RAM, SSD, Windows 7. The last 2 or 3 days it's all of a sudden been running VERY slowly. Startup and shutdown are much noticeably slower. Apps are lagging and freezing. I have up-to-date anti-virus and malware scanning apps. I've run full system scans with each and they say I'm okay. I still have 32GB of available space so it's not like my HD is close to full. I've tried running disk defrag and it just stalls out in the middle of the process. Could I have a virus or malware that isn't being detected? Could it be something else? Is there anything else I could try before dropping it off to a professional?