downgrading to Divx6 problem

Recently I was concerned that my DivX codec might be corrupted so I uninstalled and then reinstalled my version of DivX pro 6.6. After the reinstall and opening the DivX player, it prompted me to upgrade to v6.8 but instead went directly to install the current v7. When this was done I opened the DivX player v7 but it was very unresponsive and using 99% of the CPU. So I decided to downgrade back to v6 by uninstalling v7 then reinstalling v6. Now however when I open the DivX player v6 it closes itself after giving the standard "... had encountered an error and has to close.." message. Any ideas? I don't want to use 7 yet until it is stable. I have a 3GHZ PentiumD with 1GB RAM.
TIA
Paul