Error while processing

Sir,

While computing the results for my model, I got an error which says

" Failed to find consistent initial values.
Segregated group 2

Out of memory during assembly.
Last time step is not converged.
- Feature : Time - Dependent solver 1 (sol1/t1)
- Error : Failed to find consistent initial values. "

Please let me know what would be the error and what are all the probable corrections to be made??