Have you downloaded the Oblivion Script Extender? Many mods go beyond the scripts in the game and requires the Script Extender to get them to work properly and within the game's engine.
If that doesn't work, this video does have some useful tips for modding earlier Bethesda games.
https://www.youtube.com/watch?v=L7PlXXYw1Vg
Cheers for the link!
I took the time to have another crawl through the Nexus site (And installed Vortex - nice move) and discovered what the problem was with the bookcases.
I got it working, only to find its not doing what it suggested.... so deleted it!
Added a couple of things.. seemed fine.... then took the plunge and added a handful...
And now it doesn't work at all
Will be spending this evening disabling and then enabling them all one by one to find the problem.
(I KNEW this was gonna be a minefield... but I still bloody walked into it!)
Thanks for the help so far!