Loads of possibilities Steve, including spyware & adware slowing up a computer. Please don't let my doubts about this particular diagnosis put you off considering a program like spybot. Even when I was on Windows I managed to muddle through without a need but it wasn't so long back Pip asked me to look at hers (for those that know the machines, I'd say a 1ghz machine was running more like a 486) and what I found on it was a sort of horror story - it was no wonder things were slow and it took me hours by hand to get it clean again.