Please describe the problem:
I've got a png file here that causes nautilus to consume 100% cpu for about 30 seconds (on an 1.8GHz P-M) when entering the directory it contains and thumbnails  are enabled. I am, however, reluctant to share this png file, as it contains a lot of passwords (it's a screenshot of firefox's password manager I took unter windows). I tried to blur it in gimp and re-save it, but it lost its cpu-consumption properties (I did pay attention to the fact to preserve its "indexed color mode" property).

What I can give is a partial strace of nautilus:
stat64("/home/ace/Desktop/passwords.png", {st_mode=S_IFREG|0755, st_size=20005, ...}) = 0
stat64("/home/ace/Desktop/passwords.png", {st_mode=S_IFREG|0755, st_size=20005, ...}) = 0
open("/home/ace/Desktop/passwords.png", O_RDONLY|O_LARGEFILE) = 19
fstat64(19, {st_mode=S_IFREG|0755, st_size=20005, ...}) = 0
read(19, "\211PNG\r\n\32\n\0\0\0\rIHDR\0\0\2 \0\0\0062\10\3\0\0\000"..., 20005) = 20005
close(19)                               = 0
mmap2(NULL, 2588672, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb5030000
mmap2(NULL, 18800640, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xaf912000
(nautilus hangs here, resumes after about half a minute)

I don't remember how that png file was created - probably with Photoshop under windows. If the trace does not give enough information, I can try to create a new png that exposes the problem. I should also mention that e.g. feh or the gnome image viewer can open the png without delay.

Steps to reproduce:
1. Enable thumbnails in nautilus
2. Enter a directory with the problematic png



Actual results:
severe cpu burnination

Expected results:
no cpu burnination

Does this happen every time?
yes

Other information: