This is a big hole with the Access runtime. If you don't have the full retail version of Access, there is no way to define trusted locations with Access. That leaves you to modify the registry manually or add code to your application to do it. If you add code to your app, you'll still need to trust it once so it can run the code that modifies the registry.
Call this procedure from the Open event of your startup form. It checks the registry to see if the current folder is already trusted. If it isn't then it is added. I don't remember where I got this code so I can't give thanks to its author.
The code won't solve all your problems because it doesn't trust the BE location which you may also need to do but at least it shows how to create registry keys.
Option Compare Database
Public Function AddTrustedLocation()
On Error GoTo err_proc
'WARNING: THIS CODE MODIFIES THE REGISTRY
'sets registry key for 'trusted location'
Dim intLocns As Integer
Dim i As Integer
Dim intNotUsed As Integer
Dim strLnKey As String
Dim reg As Object
Dim strPath As String
Dim strTitle As String
strTitle = "Add Trusted Location"
Set reg = CreateObject("wscript.shell")
strPath = CurrentProject.Path
'Specify the registry trusted locations path for the version of Access used
strLnKey = "HKEY_CURRENT_USER\Software\Microsoft\Office\" & Format(Application.Version, "##,##0.0") & _
On Error GoTo err_proc0
'find top of range of trusted locations references in registry
For i = 999 To 0 Step -1
reg.RegRead strLnKey & i & "\Path"
GoTo chckRegPths 'Reg.RegRead successful, location exists > check for path in all locations 0 - i.
MsgBox "Unexpected Error - No Registry Locations found", vbExclamation
'Check if Currentdb path already a trusted location
'reg.RegRead fails before intlocns = i then the registry location is unused and
'will be used for new trusted location if path not already in registy
On Error GoTo err_proc1:
For intLocns = 1 To i
reg.RegRead strLnKey & intLocns & "\Path"
'If Path already in registry -> exit
If InStr(1, reg.RegRead(strLnKey & intLocns & "\Path"), strPath) = 1 Then GoTo exit_proc
If intLocns = 999 Then
MsgBox "Location count exceeded - unable to write trusted location to registry", vbInformation, strTitle
'if no unused location found then set new location for path
If intNotUsed = 0 Then intNotUsed = i + 1
'Write Trusted Location regstry key to unused location in registry
On Error GoTo err_proc:
strLnKey = strLnKey & intNotUsed & "\"
reg.RegWrite strLnKey & "AllowSubfolders", 1, "REG_DWORD"
reg.RegWrite strLnKey & "Date", Now(), "REG_SZ"
reg.RegWrite strLnKey & "Description", Application.CurrentProject.Name, "REG_SZ"
reg.RegWrite strLnKey & "Path", strPath & "\", "REG_SZ"
Set reg = Nothing
If intNotUsed = 0 Then intNotUsed = intLocns
MsgBox Err.Description, , strTitle