This is really a rather esoteric issue, but I feel I need to mention this to save someone, depending on the situation, anywhere between five minutes of googling or two hours of hair-pulling. In a nutshell, phenix gui may in some circumstances screw up other programs that use matplotlib. I can't track down which specific phenix gui action causes it, but it's safe to assume that whenever matplotlib libs are used the subsequent calls to logarithmic scale plots (and likely other things) throw this error TypeError: coercing to Unicode: need string or buffer, dict found The solution is to erase the ~/.matplotlib/fontList.cache. The likely cause is that phinix gui calls on bundled matplotlib which is different from one I have installed (not to mention that I am using Lucid (because it's LTS) which has python 2.6 and not the 2.7 that is bundled with phenix). However, it still writes into the same ~/.matplotlib folder, thus I end up with incompatible data. Certainly, the problem will be gone when matplotlib gets bumped up to 1.0.1 in next Ubuntu release. This is yet another example of why the standalone installation approach is ideologically objectionable on modern Linux. But of course, the practical advantage gained by not having to package the software for any possible OS flavor/version users may choose outweighs the lower risks of package incompatibility and the reduced size of the packaged product. -- Oh, suddenly throwing a giraffe into a volcano to make water is crazy? Julian, King of Lemurs