Hi Inigo, I checked your model in 2013 sp2.0, only about 10 parts mesh on my system. Are you sure you uploaded the most current version?
Usually when you get that message it is because there is something wrong with the definition of the material applied. Some times this happens when you import materials from solidworks and haven't fully defined them. There should be a better error message but it is better than it just failing randomly. What is usually confusing is that all the parts show a green check mark for material.
What I'd suggest is applying the material at the top level and apply it to all your bodies and see if that gets you started after you get the meshing problem dealt with.
A couple other times I've seen this is because of a cut list problem. Make sure you update it and CTRL-Q with VOR your model.
And finally I have seen some bad studies. Create a new one (don't duplicate) and drag/drop your fixtures/connections/loads but not the mesh or the materials and see if that fixes the problem. Report that one to your reseller, that would be a software issue.
But overall, you need to rethink the way you want to analyze this assembly. This needs to be done with beams. You'll have a lot of trouble down the line trying to do this with solids. If you need something with a splitline, split the beam or keep that part as a solid and add the appropriate contacts.