We had indeed some rare reports by other users for wrong strings on A6, but could never reproduce the problem. We assumed that some other parts of the scripts were overwriting string memory, maybe through loading a damaged file or using a wrong array index. Under A7, strings have some protection against overwriting, but not under A6.

Try to trace down the problem with a test script that only contains the string function, but not the rest of your code. If that test script works, the problem lies elsewhere. You can then move in the rest of your code until the problem reappears.