I have around 100 files in an archive directory with the names skeysxxx.htm. They contain message exchanges between yahoo id's which are unknown to me. They are all dated on the same day in april last, although I have only just found them whilst trying to clear some space on my HD. Apart from taking space I am not aware of any othe adverse effects and there are none from later dates.

Where did they come from and how can I prevent intrusions like this. I have ZoneAlarmPro installed, but I don't remember if it was installed last April.
rgds
kabe