If you'll pardon me, I don't think she was abused in the "beating" kind of way. I suspect she was kenneled a great deal and ignored for long periods of time. You do not mention if you have tried obedience classes with her. Sometimes this allows the dog to gain confidence because they learn the "rules" and become much better companions. It also allows you to spend special time with her and yet assert your "Alpha" status in a positive manner. Perhaps more activities that keep her out from under the bed will help. She sounds very shy to me and has no clue that the world is a fun place. Does she play at all? Does she like toys? Does she take toys with her under the bed? Do you have children that might unintentionally spook her? They're quick moving little people and not very predictable, so she may fear negative reactions (like kennelling). Does she growl when you get her out from under the bed or go limp? I'd work with her very softly in an obedience setting and then use it in the house, i.e., calling her to heel with lots of praise afterward everytime she disappears under the bed, blankets, whatever. Keep us posted and good luck.
P.S. I had another thought, have you ever had her eyes checked for lashes growing wrong, glaucoma or cataracts? It may be painful for her to keep her eyes open.

[This message has been edited by ktreva52 (edited November 16, 2000).]