Disappearing Icons And Slow Response Time?

One night I turned it on to check my email, something went wrong but I don't remember what.Anyway, I rebooted it manually and it took forever to start again.fter the starting windows screen it was just black forever. Eventually it did turn on after like 5 minutes but things didn't work well.Here's a list of problems i'm experiencing:When you drag your cursor over an icon or a taskbar icon it takes a minute for the cursor to to highlight it.Any program you do manage to click on takes forever to start. Some programs don't start at all, windows live mail tells you it can't start because there isn't enough memory left and you sholuld check your hard drive. I know there is plenty of memory left, there isn't much on that computer.

I can't do system restore, there are no restore dates available and when you try to create one it says it can't because the computer responded too slow.I can't back up my system, that also tells me the program responded too slow.AVG free virus scanner (installed after this started) can't find any virus or spyware.Advanced system care 4 (Installed after this started) found plenty of troubles and said it fixed them but everything is still broken and functioning incredibly slow.Internet works but it is slow.Every now and again the icons and start menu dissapear and come back whenever they feel like it.