Version: (using KDE 4.3.1) OS: Linux Installed from: Debian testing/unstable Packages Depending on the the zoom level, some fonts render so badly that they actually disappear. For comparison, KPDF does not have the problem. Similar to bug 195990, although I'm not convinced it's the same. The attachment will show the problem very clearly.
Created attachment 36778 [details] Comparizon between Okular and KPDF. Note the difference between the 'j' drawn by KPDF and the 'j' printed by Okular; the one printed by Okular disappears. But a smaller zoom levels the 'j' appears again. The document is a pdf version of Real World Haskell, but I'll upload a free document when I find one.
Once poppler 0.12.1 is released (in two or three weeks) can you please retest and see if the problem persists?
I can no longer replicate this. The version of libpoppler5 in Debian is 0.12.4-1 (I guess that's what you were referring to).