Hi Forester, many thanks for the kind assistance. I am running Knoppix 6.2 with the LXDE desktop. Yesterday I updated the amd/ati radeon package and also installed VLC player. The result is that Videos now play great on VLC player and despite trying for several hours this morning I have been unable to cause the slowdown at all. Things are great just now, however gnomeplayer and mplayer continue to behave erratically. If I ever get the slowdown again I'll post the TOP findings.
Thanks again!