Verical scrolling changes the explicitely set cell style to default style specified in grid descriptor

Hi,
I have a requirement where I need to populate a grid with group names & the members under each group.

Groups should be displayed as bolded text fields as sub-headers and all the members under that group should be displayed as hyper links.

So I setup this column type as anchor in grid descriptor and explicitely changing the style of only the cells containing the group names to bolded text using CSS classes.

Now, this works fine when the number of rows in the grid are less than about 50. But, if the number of rows are more then the vertical scrolling makes all the cells(including the group name cells) to hyperlinks!

I suspect that vertical scrolling when refreshing data looks at grid descriptor and displays all the cells as hyperlinks. Can anyone suggest me a solution?

Thanks in advance,
Kumar