UPDATE: I figured out my problem and how to fix it. It was indeed a 'toxic' calculation.
The LB calculator seems to choke on expressions like 'exp(10000)'. Then, every time you start the calculator, it gets stuck trying to redo the toxic calculation.
To fix, do the following
1. Invoke launchbar (apple-space)
2. type "calculator" or whatever it takes to make LB calculator the top choice
3. use the right arrow to list the last few calculations that were done.
> the 'toxic' command may not be visible. However, hit "return"; if this does not do anything, use the down arrow to select a different calculator history item and hit return again until the calculator pops up with the answer.