French power companies go bankrupt because they're hemoraging money on fusion plants, which are just absurdly more expensive fission plants, and then they go more bankrupt paying for 8-20 times more power plants than France actually needs.
The incompetence and cost is so high that the entire French government collapses and we end up with the 6th French Republic.
As this is 2007 the collapse happens just in time for the Great Recession, except with the addition of a French collapse it turns into a full blown Great Depression.
Greece goes bankrupt, followed by Spain, Portugal, Italy, the Baltics and more. The entire EU is in economic freefall and it spreads worldwide as stocks go up in flames and unemployment skyrockets.
Reeling bankrupt EU countries look to monetary policy to reduce the value of their debt, but find that due to being on the Euro they can't. Greece, followed by others, quickly sieze the Euro printing presses in their countries and declare a new currency based on their regional Euro, effectively making their own currency but with extra confusion. Conflicts from the seizures and the confusion cause the EU itself to implode, putting Europe back to the pre-EU status quo.
With no one buying their exports and an economy in freefall, Germany looks to consolidate its resources and internal market, and pushes for unification with Austria and the Netherlands, which the two even worse off countries eagerly agree to. Switzerland is made the same offer, but refuses, being relatively intact due to massive gold reserves and acting as one of the few stable currencies as the world collapses. Seeing the writing on the wall, Poland nuclearizes, and Germany does the same.
Hoping to stop Poland while they still don't have nukes, and while France, the UK, and Russia are still distracted internally, Germany launches a military offensive into Poland...