Resizing the 'Save As' window in Windows 7
Solution 1:
The window is maximized. You can unmaximize it using the keyboard shortcut Windows+Down Arrow or by double-clicking the title bar. (That there is no unmaximize button and the resizer doesn't work can certainly be considered a bug.)
Solution 2:
This works for Windows 8 - it may help you on other windows versions. Click Alt-spacebar. you should get the little action box in the upper left of the screen. Click on Restore. This should re-size the save as window, and allow you to use the mouse to drag the screen size to your desired size.
Good luck.