Workbooks opens in Read Only mode and I don't them to.

I have two workbooks I have used for months and suddenly whenever I open them, they open in read only mode.

When I try to save them, I'm told to rename using different names.

Did as requested. When I open either freshly re-named file, it too opens in read only.
Several iterations produce the same result.

When I go to Properties>General it shows the read only box as being checked but it is grayed out for both.

I didn't change their status consciously and don't know to fix them.

Several other workbooks I tried don't have the problem.

The only thing that has changed recently is my update from Snow Leopard to Lion 10.7.3.