A version 4.0.5 spreadsheet malfunction warning.

I just downloaded and installed version 4.0.5, but when I “Insert row” in my spreadsheet, the whole spreadsheet goes blank, and some weird red triangles appear in it.
Discarded 4.0.5 and reinstalled 3.6.5, works OK.
So be warned.
Using iMac MA877LL under OS 10.6.8