Hi, i'm new about PC so i don't know what is the problem with my thing.

Well 2 days ago, i was shutting down my PC but the PC wasn't going to shut down for 5 min and stay at desktop, after i got a message " Window Explorer has stopped working" ( while the message is pop-up, my PC is slow and lag like hell, it took me 2 min to close the message 'cause the mouse wasn't lag and hard to control) and then i closed the message, PC shutdown normaly. And the next day, my PC became very lag ( if i open 2 tabs on Firefox, PC gonna freeze ) even right-click on a game icon at desktop, it takes 20 seconds to show me the option to copy or cut or ect... I tried to delete everything ( games, yahoo, ect..) but the problem still there. I'm using Dell 14R inspiron with Window 7 x32 bit.

If some1 has the same problem and fixed, please help me :(

And sorry for my bad english