Joe, the trick is that you do not specify exact alias name in recno() function suggesting that it is always current alias as it is after 'select tranfile'. Than, you assign DynamicBackColor - its ok. However, when user made some actions on the form, current alias changed from tranfile to other workarea where no any cursor opened. So recno() function no longer valid because no cursor opened in current workarea. When grid refreshes, it try to calculate the DynamicBackColor expression and fails.
SO, to avoid such problem, use recno("tranfile") inside of DynamicBackColor expression, like following:

PUBLIC grno
select tranfile
grno = RECNO()
THISform.pageframe1.page1.grid1.setall("Dynamicbackcolor", ;
"IIF(RECNO("tranfile")=grno,RGB(128,192,192),RGB(255,255,255))","Column")


>Thanks for the suggestions. Either way I'm still getting the error periodically. Here's my exact code in the different places I have them:
>
>---AfterRowcolChange
>LPARAMETERS nColIndex
>select tranfile
>grno = RECNO()
>THISform.pageframe1.page1.grid1.setall("Dynamicbackcolor", ;
> "IIF(RECNO()=grno,RGB(128,192,192),RGB(255,255,255))","Column")
>select receipt
>THISFORM.PAGEFRAME1.PAGE1.REFRESH()
>
>----Grid Init
>PUBLIC grno
>select tranfile
>grno = RECNO()
>THISform.pageframe1.page1.grid1.setall("Dynamicbackcolor", ;
> "IIF(RECNO()=grno,RGB(128,192,192),RGB(255,255,255))","Column")
>
>----Grid Refresh
>select tranfile
>grno = RECNO()
>THISform.pageframe1.page1.grid1.setall("Dynamicbackcolor", ;
> "IIF(RECNO()=grno,RGB(128,192,192),RGB(255,255,255))","Column")
>select receipt
>
>Thanks.
>
>Joe