Nalates Urriah has a blog post on her blog and a forum post in the official forums regarding problems on the Aditi grid. Aditi is the preview grid, you can read more about it here. Basically this is where Linden Lab sometimes roll out server code for testing, or new features. This is part of the Q&A process.
Customers use it for other matters, I use it for playing around with Mesh, others use it for testing their products because Aditi is a place where you get a wad of Linden Dollars to play around with, so uploads are basically free. However bear in mind that what happens on Aditi, stays on Aditi, you won’t be able to bring your dosh across to the main grid, nor your uploaded products, you’ll need to upload on the main grid again and pay for them.
Now the issue seems to be that Aditi is creaking a little, it’s not a mirror image of the main grid, it has far less land and far less resources. Therefore it requires some housekeeping. Oskar Linden used to do this housekeeping, but of course, Oskar has now left the building and new solutions are being sought. I haven’t had any problems logging into Aditi, but it appears plenty of others have.