  A (n+1)-dimensional gravitational model with Gauss-Bonnet term and
cosmological constant term is considered. When ansatz with diagonal
cosmological metrics is adopted, the solutions with exponential dependence of
scale factors: a_i ~ exp( v^i t), i = 1, ..., n, are analysed for n > 3. We
study the stability of the solutions with non-static volume factor, i.e. if
K(v) = \sum_{k = 1}^{n} v^k \neq 0. We prove that under certain restriction R
imposed solutions with K(v) > 0 are stable while solutions with K(v) < 0 are
unstable. Certain examples of stable solutions are presented. We show that the
solutions with v^1 = v^2 = v^3 = H > 0 and zero variation of the effective
gravitational constant are stable if the restriction R is obeyed.
