Debugging Memory Allocation

Recently I was debugging some particular nasty bugs that happens on memory allocations, the intricate part is, it happens infrequently My app was crashing on a release build more frequently than in debug builds.
I was doing some manual memory allocations, at the start of the app it will load a saved data from a file into that memory. The app was doing fine until I started to write something to the saved data, then on the next launch it will start to crash intermittently on release build.