Dave,
Here is my script. It Functions just fine, except for the fact Impromptu App does not close down. It does not even close the report...(excuse the line-wrapping)
Dim ImpApp As Object
Dim ImpRep As Object
Sub Main()
Set ImpApp = CreateObject("Impromptu.Application"

ImpApp.OpenCatalog "F:\Program Files\Cognos\e-Applications 1.0\BI\Catalogs\mssql\BIC_SA_CUSTOM.CAT","Creator"
Set ImpRep = ImpApp.OpenReport("F:\Program Files\Cognos\e-Applications 1.0\BI\Reports\Roller Reports\Roller Shipments2.imr"
ImpApp.Visible True
AppActivate "Impromptu - [Roller Shipments2.imr]"
SendKeys "%F",1
SendKeys "A",1
SendKeys "{TAB}",1
SendKeys "{DOWN 8}",1
SendKeys "{ENTER}",1
SendKeys "+{TAB}",1
SendKeys "\\MLFFSS1\IT\OneWorldQueryDoc\Roller Ships2.xls",1
SendKeys "{ENTER}",1
Set ImpRep = Nothing
Set ImpApp = Nothing
End Sub
When I put in the ImpApp.Quit command just prior to the SEt ImpRep = Nothing command, it runs fine up to that point, actually creates the output file. But then it either just leaves Impromptu open anyway, Or gives me one of two error messages : Either the Memory cannot be Read application error or it gives me Error Code 1003 - Exception not handled by program.
The only time it actually closes down the app is when I generated the Memory Error.
Also - I tried using your dynamic file name in the SendKeys statement -- it doesn't gets stuck where it should be replacing the old filename with the new file.