This generally is an indication that you have an ill-conditioned matrix, which is often caused by having non-isolated solutions. This can be because you have floating parts of you circuit - which means there is potentially an infinite continuum of solutions, and this is a problem for convergence.
It can also be an issue with certain loops (e.g. loops of ideal inductors, voltage sources in parallel and so on). The topology checker will find many (but not all) of these.
I'd suggest that you contact customer support so that we can take a look at your example and give some directed advice?