[quote]256 Megabytes Installed Memory
Norton internet security[/quote]
My instinct would be that the above info is a lot of your problem -
256MB RAM is not much - see if you can add another 512 - that will cost you about £40 or so.
Norton uses a lot of resources - when your licence expires, I'd suggest you get one of the free alternatives.
If the problem has only just begun, however, I'm not sure what to suggest.