It's probably not exclusive to just that spot either. A big chunk of objects with a large amount of pure virtual functions that can be called from anywhere makes a lot of places potentially responsible, but just one location should be enough.
Regardless, it's helpful to report what the stack looks like when you get the error. Open blockland, attach ollydbg, click debug->run to resume execution, and wait for it to happen. Once the error occurs you'll want to navigate to the bottom right window (which is the current state of the stack):

Then right click edit->select all, edit->copy as table, paste into a text file/pastebin and report back here.
The stack is important because it holds a chain of return addresses eventually leading to the culprit function. It's very useful when tracking down exactly what situation caused the crash.