The problem I think boils down to the fact, that integrates 1/x as log(x), even if x < 0. The attached file gives more instructions suffering from this problem.
Can you please describe the problem here for those who do not use wxmaxima?
Integrating 1/x gives log x, instead of log |x|. If assume(x<0) Maxima nevertheless has no problem with plotting log(x) between [x^, 10^6, 10], and simply calls the assume inconistent. I will post ab html-file with more details.
See, for example, http://www.math.utexas.edu/pipermail/maxima/2009/017190.html.
I think this is the expected behavior.
Changing category to integration.
Closing this bug report because it is the expected behavior of Maxima. See comment in the last posting.