When using Avogadro on a French Linux workstation, it is not possible to draw a molecule. The sketch window becomes frozen. The bug may be due that in French locale, the decimal separator is a comma (',') and not a point ('.'). To avoid the bug, the program has to be launched with the following command:
$ LANG=C LC_ALL=C LC_NUMERIC=C avogadro
The bug can not be reproduced with Avogadro v1.0.3
In years of using Avo on a french Linux box, I never encountered this situation.
Presently, CentOS-5.7, Avogadro version: 1.1.0 Git: 834b7e7.
It would be interesting to know which Linux distribution you are using and whether
you compiled from sources or installed a pre-built version.
Louis