It might show up looking normal in the pic, but Im just guessing, so try anyways. I would delete, and then reinstall the latest nightly build of chimera. That doesnt happen on mine, or anyone else's to my knowledge.
i often have a problem with portions of text disapearing in chimera (sometimes flickering on and off depending on what i'm doing). i think that there are still several bugs to be worked out in getting the gecko rendering fully quartz compliant. keep in mind, it's only on .5
99.9999999% of all text rendering issues I ever had with Chimera were fixed by Jaguar. If you aren't running Jaguar, thats already one big setback, but it seems that pretty much everyone on these boards already is.