HELP??. Bug in DBGrid updating with Record Numbers

I have created a calculated field for retrieving the record number
(Paradox) for display in a DBGrid. I am using Borlands TI2869 retrieve the
record number with the BDE using DbiGetCursorProps and DbiGetRecord .
Doing this corrupts the display in the DBGrid, with some records repeated
lots of times and appearing once out of turn.
I have tried it with Borlands DBGrid and woll2woll's grid and as they both
display the same problem, it seems to be an inherent flaw in the system.
Has anyone come across the problem and found a solution to it?