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You answered it good enough. I can just use the older version. I would probably lose more then I would gain messing with my rig drivers.
Actually, the most likely cause is the fact that you have already messed with them.
(whether you realise it or not)
I renamed the original cgminer as a backup, and did a fresh install of the new version with a copy of the config file. I then realized the hashrate was wrong, deleted the new copy and renamed the original and its working fine again. What could have been messed up?