I am also receiving this issue, as is every member of my Free Company at the moment.

It seemed to have started when some of our officers were using the Company Chest to move Furniture from one alt character to another. They were specifically using the 3rd Item Tab.

We are able to use Tabs 1 and 2, but Tab 3 is completely broken, and attempting to move, deposit, or withdraw items from it will result in a 90000 error.