Hi Natalie,
I guess your button uses
DoCmd.RunCommand acCmdEditHyperlink
on a control that's bound to a hyperlink field.
If the field is empty, the Edit Hyperlink dialog opens at the current
folder and I don't think there's any way to change that. But if there's
a value in the hyperlink field, Edit Hyperlink attempts to open in the
corresponding folder.
So maybe you can achieve what you want by either
(1) setting a default value for the hyperlink field, or the textbox
bound to it. This default value
C:\Temp#C:\Temp
makes Edit Hyperlink open in C:\Temp.
Or (2) have the code behind your button set the field to the appropriate
value before calling EditHyperlink, e.g.
Me.MyHyperlinkControl.Value = "C:\Temp#C:\Temp"
Me.MyHyperlinkControl.SetFocus
DoCmd.RunCommand acCmdEditHyperlink