Thank God For "System Restore"

I upgraded my Yahoo messenger the other day and since then I could do nothing with my computer. I restored the system this afternoon and it's working again. I don't know what it was but I often could not navigate and frequently could not turn the Internet Explorer off. It was probably clashing with another program. My anti-virus and spyware programs both say nothing is there so it was probably just a clash with another program somewhere. I don't need an advanced Yahoo messenger anyway.