Firefox - Half of GRID disabled while sorting

Hi,

I am testing out the grid in IE and firefox 1.5.0.4. Everything is working fine in IE but not in firefox. For every first sorting action the data in my grid goes blank or i can say half of part is disabled.

for example:

The grid loads fine with all of my data in it but if I click on a header to sort the data, the half of GRID is disabled and half is enabled. so i can see only half of data rest of upper half with header is disappers.

Then if I agian click on another row then the whole data reapears and GRID is set to proper(Original) size.

Has anyone come across this? please suggest me any solution.

Thanks