Something's got her stressed out. I'll always choose a tub over a tank - but I know tubs aren't for everyone.
Instead, to help her settle - fill her enclosure to the brim with very lightly balled up pieces of newspaper. This will allow her to feel more secure, she'll have something touching her at all times, and you'll find that she'll settle rather quickly after that. Then you can slowly "wean" her off the paper by removing a piece or two every few days. You can also feed while the paper is in there, just drop the mouse right on in - she'll find it!
Credit for this tip goes to Kevin McCurley of NERD. Myself and every member who's tried it can attest that it works.