Matrix too large for single precision - try iterative solver

Solution: 

This means that the electric window is too big for the single precision version of the code. There are a few ways to fix this:

1. Change to the double precision version (Options->Settings->Executables-> double precision button)
2. Try a different solver PIEZ SLVR - DCGD is usually the most efficient
3. Optimise your electric window through PIEZ WNDO AUTO PIEZ