Seems that my VS2008 help index has finally become FUBAR. It's already a known issue that after installing SQL Books Online 2008 SP1 a lot of inter-topic links break down, but this is even worse. When index entries start pointing to completely unrelated topics and things like "System.Collections.IList namespace" appear - then you know you are in trouble.
So... is there a way to regenerate the index and whatever other data structures the help has? I don't want to reinstall it to factory defaults, because there are quite a few other help collections in there too and I don't want to lose those.
Try H2Reg. I fixed my VS2005 help collection after an old version DevExpress broke it. Another option is to remove/add every product's every components that rely on the same version of help system, reinstall if the product does not have a separate option for help, which is probably not what you want to do.