Whenever there's a tragedy involving a cake layer sliding, there also tends to be some type of fruit filling involved.
First of all, if you have sleeved strawberry fillings anywhere near you, go throw those away because they're the worst offenders. I've written about strawberries before, and this video shows the same method I described in that post a while ago:
Make sure to encapsulate your fruit and you shouldn't have any issues with sliding layers. Also, avoid frozen fruit since that weeps more liquid than fresh fruit does.