For various reasons, my Mac had to completely redo its Spotlight index. But it was taking far longer than I expected, chewing up a lot of hard disk bandwidth (and keeping my laptop fan on all night). That's not good.
I investigate with Activity Monitor and find that mdworker32 is doing a lot of work. That's the program that, in the background, builds up the Spotlight index so you could search for file names and contents. It relies on various Spotlight plugins (mdimporter) that lets third-party programs define how its own files is to be indexed by the whole Spotlight system.
Opening up the Console program lets me see all the log files that's been generated lately, including a lot of mdworker32 crash logs. Each of which finger the com.smarttech.notebook.mdimporter plugin as the crashing culprit. It even helpfully identified its location: /Applications/SMART Technologies/Notebook.app/Contents/Library/Spotlight/SMART Notebook.mdimporter.
Completely removing the /Applications/SMART Technologies/Notebook.app/Contents/Library/Spotlight folder fixed the problem.
It turns out that whenever Spotlight indexing encountered a SMART Notebook file, it tried to use the SMART Notebook.mdimporter plugin, which promptly crashed, triggering mdworker32 to relaunch to keep indexing. Of course, the SMART Notebook.mdimporter plugin kept crashing mdworker32, so Spotlight indexing was taking forever and getting nowhere fast.
This fix does mean that Spotlight can't do a content-based search into SMART Notebook files. Of course, it still couldn't even without the fix given that the mdimporter pluging wasn't working to begin with. Maybe my SMART Notebook is old; it's version 11.0.811.1.