I am using ink-scape as a primary tool of drawing. I like its expandable features in the form of extensions. I downloaded a number of extensions from ink-scape extension repository.
When I try to apply some extension (like: perspective) it shows a dialog indicating a caution as under:
"
Inkscape has received additional data from the script executed. The script did not return an error, but this may indicate the results will not be as expected.

Traceback (most recent call last):
File "/usr/share/inkscape/extensions/perspective.py", line 21, in <module>
import sys, inkex, os, re, simplepath, cubicsuperpath
File "/usr/share/inkscape/extensions/inkex.py", line 23, in <module>
import xml.dom.ext
ImportError: No module named ext
"

How can I deal with issue.
I am using Inkscape 0.47 on Ubuntu 9.10 x86_64

For some reason you seem to have a very old version of inkex.py. Try replacing it with the current version.