Macro - browse for file problem

I have a macro that takes data from an excel file and imports it into CorelDraw. 

The code below is what I am using to pick which files I want the macro to use.  The first time I open CorelDraw to run the macro, it works perfectly.  However, if I leave the CorelDraw window open and then run the macro again, the "open file" dialog box is hidden (I have to use alt-tab to select it so I can choose the correct excel and CorelDraw files).  

Any idea what is causing this problem?

Private Sub cmdSource_Click()
Dim str As String
Dim objFileDialog As Office.FileDialog
Dim objFileDialogFilters As Office.FileDialogFilters

Set objFileDialog = excelObject.Application.FileDialog(msoFileDialogType.msoFileDialogFilePicker)
If CSVInitialFolder = "" Then
CSVInitialFolder = "C:\Users\mypersonalcomputer\Desktop"
End If
With objFileDialog

'define a Filters object
Set objFileDialogFilters = .Filters
With objFileDialogFilters

'clear the default filters

'add a filter, all filters must start with an asterisk
.Add "CSV Files", "*.csv"
.Add "Excel files", "*.xls"
End With
.InitialFileName = CSVInitialFolder

'allow only one file to be selected
.AllowMultiSelect = False
Dim hxl As Long
hxl = FindWindowA("XLMAIN", "Excel")
If (hxl <> 0) Then
res = SetForegroundWindow(hxl)
End If
'show the dialog and exit if Cancel is pressed
If objFileDialog.Show = 0 Then
Exit Sub
End If
End With

txtCSVFile.Text = objFileDialog.SelectedItems(1)

CSVInitialFolder = Left(txtCSVFile.Text, InStrRev(txtCSVFile.Text, "\"))

End Sub