Post any defects you find in the released or beta versions of the ImageMagick software here. Include the ImageMagick version, OS, and any command-line required to reproduce the problem. Got a patch for a bug? Post it here.
It appears there might be a bug in the pdf.c coder. The Visual C++ Debug Library kicks back an error saying that the variable 'code' is being used without being initialized.
I know for a fact I'm using a bad .ai file. IM delegates to GhostScript, which fails. However, it looks like IM is not absorbing that exception well.
We added a patch to ImageMagick 6.6.6-7 Beta to fix the problem you reported. However, for deeper testing, post a URL to your image here and the command you used. We'll verify the patch is working properly. Thanks.