We study the stability and instability of ALE Ricci-flat metrics around which a Lojasiewicz inequality is satisfied for a variation of Perelman's λ functional adapted to the ALE situation and denoted λ ALE . This functional was introduced by the authors in a recent work and it has been proven that it satisfies a good enough Lojasiewicz inequality at least in neighborhoods of integrable ALE Ricci-flat metrics in dimension larger than or equal to 5. Contents 1.2. The functionals λ 0 ALE , m ADM and λ ALE 1.3. Main properties of λ ALE 2. Preliminary estimates for short and large time 2.1. Heat kernel Gaussian bounds 2.2. L 2 − C 0 estimate 2.3. Weighted estimates 3. Stability of Ricci-flat ALE metrics 3.1. A stability result 3.2. Proof of Theorem 3.1 3.3. Evolution of the Bianchi form, the scalar curvature and the mass 3.4. A discussion on previous stability results 4. Instability of Ricci-flat ALE metrics 4.1. A priori energy estimates in the unstable case 4.2. A digression on λ ALE 4.3. An unstability result Appendix A. First and second variations of geometric quantities References Date: today.