Can reproduce it in Drawing and Impress with DEV300m37 on WinXP and Ubuntu

How to reproduce it 
1 Create a new Drawing (or Impress, it's up to you) document
2 Insert - table, 'Insert Table' dialog appears, set 'Number of column' and
  'Number of rows', e.g. 5columns * 12rows, OK
3 Select 3 row cells from the last row/line at one or more continual columns
  in the table, hit 'Merge Cells' on Table bar.
4 Select the merged cell formed at step3, meanwhile from the one or more
  continual columns which are next to the merged cell formed at step3, select
  3 cells from the last row/line, hit 'Split Cells' on Table bar, click 'OK'

Result
OOo crashes

Expectation
OOo works well

Attention
It's an arithmetic progression problem, I think.
supposed that there is a table with m rows and n columns, the number of cells
to make merge cells is x. Now, there are the rules for this issue
if x = 3, just select cells from n to n-2
if x = 4, just select cells from n to n-3 or n-1 to n-4
if x = 5, just select cells from n to n-4, n-1 to n-5 or n-2 to n-6
...


If my description is not clear, feel free to ask me anything anytime.

Regards
Li Meiying