I had to reinstall and reconfigure a MOSS 2007 server after a corrupt installation.

Went I reattached the old content DB it showed no problems, and I could see the old site collections added to my web application.

But when i tried to surf to the url of the site collection I got a http 500 internal server error.
At first I thought I hadn't installed / configured the new IIS on the server correctly, or the version of the content DB and moss installation wasn't the same. But when i created a new site collection in the old content db it worked perfectly.

After hours of searching I came to the conclusion that the existising site collections were created in dutch, while my new installation did not contain the language packs.
So when in doubt and your not sure about the content your importing, try installing language packs for MOSS 2007...