That was at the end of June.
In August, they spent about €2.2 billion buying out Siemens' stake in Nokia Siemens Networks. This could very well have caused some short-term cash flow issues. Which also explains Microsoft's offer to finance Nokia at extremely low interest bonds.
Long-term, NSN is generating positive cash flow and ought to be able to pay for itself.
Either Microsoft is completing a long planned purchase, or Nokia threatened to dabble in Android. Other than that the purchase is irrational.