Hello. The drop-down list that normally contains the units for applying transformations shows up empty on my system. I linked a screen shot below.
(Ordinarily, there are options like %, px, mm, etc.)
This only occurs with the portable version of Inkscape. I'm using InkscapePortable_0.48.1.paf.exe on Windows XP (Service Pack 3).
I apologize if this is a known issue. A few, cursory searches provided no results.