xen2xen1

I don't think the launcher does just maps... Techincally, you could make a "modpack" that does nothing but load a saved world. It just unzips what you put in a zip. IE, if you make a zip with: \saves\MyGreatMap inside it, including the directory, it would just unzip that file and throw night but that saved world into a fresh Minecraft build. Modstechnically are not required, I believe.

What modpack, are you using solder or just a big zip, and you're putting the Flan content mods in that \Flan folder, and not in with the mods, right? You know you can make a zip with a Flan folder inside it? Basic questions.

What's the name of the modpack to test it? Stolen from another thread: I've found that DropBox does something to the archive (rare cases) where it changes the MD5 checksum between what's on your machine and what is downloaded. Have you tried another service like OneDrive (microsoft), or even maybe some other service? I personally use a dedicated server to host my files (thru solder). You could get yourself a cheapo web page hosting site (most come with 500MB of file storage) and use it to host your files. The reason I say this, is because when (not if) your pack becomes popular, DropBox will throttle your download and eventually block it entirely. But the thing to check would be your checksums between what you are uploading and what is stored on DropBox to start. Also, check this forum post about DropBox: DropBox breaks technic platform links At the bottom of the OP, it mentions using copy.com as an alternative.