I have installed the latest ImageMagick version 6.3.6-1 on my Windows XP (SP2) system, together with Ghostscript 8.60.
When I try to convert the following PDF file the resulting JPG image is not correct.
PDF file to convert (9 MB!)
The bogus result looks like this

but I would expect an image like

When I use an old ImageMagick version like 6.3.2, the result is perfect.
The same bug occured once on IM 6.3.3, but you fixed it and now it seems to be back.
I am using this convert command:
convert -profile ./cmyk.icc -profile ./rgb.icc -resize "300x300>" ./sample.pdf -colorspace RGB ./test.jpg
You can download the color-porfiles here, but you can also reproduce the bug without the profiles.
cmyk profile
rgb profile