Since you seem to have isolated the problem to the point where the script is "loading items into the Treeview", the next step might be to try one of the following:

• use the debugger to step into the Treeview loading process, to see if there is a specific point where the fault occurs (this could be quite tedious, depending on the amount of data being loaded, and where the problem happens in the data set)
• try using different amounts and types of input data -- and take some other form of dump from the MLDBM file, to check its contents for unexpected "features".

It might be easiest to try varying the input data first, to see whether it crashes under all conditions (in which case, present a simple demo of the problem to the module author).

If it works for some data sets and not others, the issue is either the quantity or the quality of the data. Let's suppose it's crashing on data set "X"; try to divide that set into two or more pieces of fairly equal size, such that it runs okay with just the first piece, then run it on the other pieces to see if those work as well. If it crashes on any of those other pieces, you know where to look for a data quality problem; otherwise, it's a limitation on quantity (in which case, the module author might want to know).