When inserting rows at some distance from the cell containing the summation, then the summation area (and the sum result) is changed in severely wrong manner - totally unexpected.
Some complex spreasheets of mine have been affected by this bug during the last months —> so I’ve been obliged to return to MS Office!
I’ve reported this bug here [link text] https://bugs.freedesktop.org/show_bug.cgi?id=77080 You can download the attached zipped file containing a spreadsheet and 2 screenshots. Open the spreadsheet and insert a few empty rows in the position shown by the screenshots, to repeat my experience.
Libre Office Version: 4.2.3.3
Build ID: 882f8a0a489bc99a9e60c7905a60226254cb6ff0
language: English, component: Calc
OS: MS Win7 Ultimate 64-bit SP1