I think he is probably referring to the fact windows thinks it is installed still, even though you have removed the files. A Registry clean up may work. (Reg clean, if it works on win 7) would possibly fix it. You could check the registry manually for darkmatter etc and remove them. Or you could attempt a system restore to a point before you started changing things. Just remember windows 7 system restore can revert a lot of things so be careful, you wouldn't want to lose anything you worked on last night for instance, if restoring to 3 days ago. If none of those ideas appeal, try installing them to a different directory instead of the default one. Dark matter should be easy enough to get the models even if the install doesn't work I would imagine.
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