I struggled that last two days with the above problem:
- I had a spread sheet a was happily working with.
- At some point I made a change that caused calc not responding for several minutes when opening, modifying or saving it.
I looks like calc steadily hanging in the first place. However after serveral (10 - 15) minutes of high CPU load it came back - until the next modification.
=> I was not able to work with this spread sheet.
I did not find a solution in the web.