Try Internet options.Advances and press reset advanced settings and see if that helps.
Or you can press reset underneath that which will reset I/E8 to its original condition but you may loose your favorites.
There have been a few updates recently for Java and Flash programs make sure you have the latest updates for both and all old versions removed.
If still not working properly try Firefox till you get I/E8 working properly again.
Give C Cleaner a run if you have it.
Old computer check the air vents are clear of dust and fluff if so inside will need cleaning out as well.