I have downloaded QGIS dev version 1.7.0-114 and I have come across some weird behaviour in the composer.
I create a map with a hillshade and a transparent DEM ontop of it, pretty standard stuff. When I export this map to an image format I get two strips across my output, this happens for a number of formats (png, jpg, bmp, tiff) and the stripes seem to be in the same place everytime. I have attached an example below (sorry for the size of the attachment).
The stripes appear in the same position on the page every time and this happens with different raster datasets, so I have ruled out the data.
Also depending on the page size you may get 1 stripe (A5 as shown above), 2 stripes (A4) or no strips (custom dimensions h100 x w100).
Is this something that can be overcome via some settings which I may have overlooked? Or might this be something funny in the software?