I've seen an error message quite similar to that in my own toolset, after I tried opening a mod where a hak for it was already open in NWHak. The mod load failed, and I got that error everytime I tried to do anything in the toolset after that. In my case, simply closing the toolset and reopening it fixed it, which isn't the case for the OP since it's persisted this long, but that was the cause of it for me. An incorrect mod load/initialization, from a hak issue.
I was wondering if this is a new module? Are there haks in it? Does it happen regardless of what module you try opening?
If there are cases where it reacts differently it might help in narrowing the cause of it down some.
