I recently ran into a problem, which didn't immediately make itself clear (this is one of the troubles that django causes me -- too often the error reporting is just not there, and forces me to do a good deal of debugging to even determine where the error is occurring).
After facing several unpromising "500" errors (well, they were really 404's "page 500.shtml not found..."), I broke down, tunneled in and started the devel server. At this point, the error was made plain; python was all-out dying, with the cryptic message AccessInit: hash collision: 3 for both 1 and 1.
[for the impatient, you can jump down to The Solution ]
What I got from these posts was that somehow, PIL was getting imported twice, or something, and was choking because of it. But the question remained as to how this could happen.
So, I dove into the source code, and several unscrupulous print statements later, I traced the problem down to my use of the "Pygments" module, which in turn uses PIL.
The offending statement is in pygments/formatters/img.py, line 21
# Import this carefully try: import Image, ImageDraw, ImageFont pil_available = True
The problem is, that in Django, PIL is imported thus
from PIL import Image, ...
This is confusing to python, which thinks that these two "Image" modules are different, when they are in fact the same. (I found several people on the internet bemoaning this double-standard of PIL usage). I fixed this by changing the Pygments module to use the from PIL import syntax.
Unfortunately, this wasn't the end of my problems; I also use the docutils module, which again tries to "import Image", causing the hash collision. Luckily, it wasn't to difficult to track those instances down and kill them...I mean fix them. Anyway, I ended up with the following two patches, which restored my system to working order.