The OpenACS config file hasn't been updated for AOLserver 4.0 as almost everyone here uses the OpenACS distribution of AOLserver, which forked from the AOL version a long time ago. Merging the distributions is a recent effort, coinciding with work on the 4.0 branch which includes several other improvements.
nsrewrite isn't actually used by OpenACS so you can remove it from your config file if you want. The module itself is in transition from OpenACS to SourceForge. nsdb as a separate module is an AOLserver 4-ism.
I'm glad you found a solution to your problem!