MC7 "preparing to export" ... but never finishing

Hello,

I am editing a wedding video on Avid Media Composer Interplay Edition 7.0.2. Final sequence is about 25 minutes long, and I want to export it as an H.264 QuickTime file. I start the export and Media Composer says "preparing to export" for many, many hours. Is it normal for that stage to take forever or is the software stuck?

Thanks,
Dan

Windows 7 Professional 64-bit

i7-3612QM @ 2.10 GHz | 8GB RAM | Intel HD Graphics 4000 + GeForce GT 640M LE (2GB) | Samsung SSD 840