copying a rectangle causes uniconvertor crash

New drawing, draw a rectangle, copy and paste - and the following comes up again and again and again. Even after closing inkscape (using the menu, the close button has ceased to work, these messages keep coming two a minute.

"UniConvertor failed:

Cannot load plugin module sk1saver
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/uniconvertor/app/plugins/plugins.py", line 73, in load_module
    desc)
  File "/usr/lib/python2.7/dist-packages/uniconvertor/app/plugins/Filters/sk1saver.py", line 249, in <module>
    from app.Graphics.image import CMYK_IMAGE
ImportError: cannot import name CMYK_IMAGE
When importing plugin sk1saver
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/uniconvertor/app/plugins/plugins.py", line 190, in __call__
    module = self.load_module()
  File "/usr/lib/python2.7/dist-packages/uniconvertor/app/plugins/plugins.py", line 73, in load_module
    desc)
  File "/usr/lib/python2.7/dist-packages/uniconvertor/app/plugins/Filters/sk1saver.py", line 249, in <module>
    from app.Graphics.image import CMYK_IMAGE
ImportError: cannot import name CMYK_IMAGE
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib/python2.7/dist-packages/uniconvertor/__init__.py", line 88, in uniconv
    saver(doc, output_file)
  File "/usr/lib/python2.7/dist-packages/uniconvertor/app/plugins/plugins.py", line 194, in __call__
    % {'name':self.module_name})
app.events.skexceptions.SketchError: Cannot load filter sk1saver"

Inkscape 0.48.3.1 r9886
Ubuntu 12.04 LTS
installed through Ubuntu software center

At first attempt, the missing path //home/.uniconvertor was also complained about, the message included came after I provided that one (empty). I tried leaving out the wmf-converter extension on installation but no joy. Seems like some packages are missing but I don't know which ones and where to get them.