Even if the sysrq key is disabled, most systems automatically invoke the oom killer. If your work is super important, just let your system sit for a day or two the problem may resolve itself.
If you don't get any logs about why it locked up I recommend enabling kernel message logging to disk.
Great question I've been wondering the same thing. I've been using a spreadsheet with some fancy lookup sheets for far too long, which results in only one 'category' of expenses ever being tracked.
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