If you're a PC user (meaning microsoft windows user) then you've probably experienced a slow down of your PC and if not a slow down, a time when your PC just won't respond.

One of the most likely cause of a slow or unresponding PC is that your PC is running too many programs at the same time. Now closing your running programs doesn't actually close the program because some of the programs are still running in the background.

If you've already closed your internet explorer (a program which is a memory hog especially if you have too many tabs running) but your PC is still slow, try bringing up the task manager by pressing ctrl, alt, del at the same time and go to the processes tab. If internet explorer is still running in the background, you will see the iexplorer.exe running in the background. You can end this task immediately to free up some of your PC's memory.

You can also try ending some unnecessary processes like msn.exe or other programs which you have closed but are still running on the background. To check if the process is a necessary windows process, you can try googling it since there are a lot of process library websites which can help you decide if the process is necessary or not.