Dell Inspiron N5110 not working properly!!!

My laptop has been acting up lately. It would start up just fine but would become really slow and the programs would stop responding and then It would come up with the message that "Windows Explorer is not responding." Then when I try to shut it down it would just stay at the logging off screen with the circle spinning and spinning. The max it would correctly for is 5 minutes max. I am writing this from a different computer. Please help me.I have ran virus scans and disk's checks. I do not know what to do know. I also tried to restore the computer to a to a previous version but it stayed at the 'System Restore is initializing..." screen for a whole day!!!