I am using Inkscape v0.48 on Windows 8.1 64-bit. Though I can access it initially when I open a file, after I do really any sort of other work, I become unable to modify the location or dimensions of an object via the numerical tool in the toolbar. In fact, the location and dimension often cease to load when I go into selection mode (the topmost mode) and select the object; instead those fields in the toolbar are blank and cannot be edited. I try clicking other objects and have the same problems.

What could be causing this?

EDIT: I often have to close Inkscape and reopen it to do any more modifications.