installation of contrib modules broken?!

Using the current CVS version (as of the time of this post) I can no longer install a new contrib module. The module shows up in the admin >> modules listing (unchecked), but no entry is created in the system table in the database. So checking the checkbox to enable the module does nothing (comes back unchecked).

I found this out in an attempt to "reset" the views module with the following procedure. (1) delete all views, (2) drop all views tables, (3) delete modules/views.module row from systems table, (4) re-enable the views module to recreate tables etc. Thinking it might have been something peculiar about views having been previously installed, I tried it with a module I've never had installed (relationships), with the same symptoms.