VBScript Outlook encounters encrypted email producing error 'Entrust Entelligence Security Provider' - email

Question

I have an HTA and using VBScript to loop through Outlook email folders and get folder size. The HTA is run on a shared drive by staff, it is not an administrator tool. On occasion, my company will send encrypted emails. When the VBS hits one of these emails, the following happens:
1) VBS pauses.
2) Outlook displays the 'Entrust Entelligence Security Provider' error and asks the user to click 'OK'.
3) Once OK is clicked, the VBS continues.
The Outlook message does not bring focus to Outlook, so it is possible the user will not notice the message and continue to wait for the VBS to finish.
Is there any way of avoiding this message?
Here is my code:
public TotalSize
Sub OutlookDetail
TotalSize = 0
msgbox "Depending on the size of your Outlook account, this process may take up to 60 seconds" & vbcrlf & vbcrlf & _
"If you have encrypted emails, Outlook will make a sound and give you the 'Entrust Entelligence Security Provider' message. Click 'OK' to proceed."
Const olFolderInbox = 6
Set objOutlook = CreateObject("Outlook.Application")
Set objNamespace = objOutlook.GetNamespace("MAPI")
Set objFolder = objNamespace.GetDefaultFolder(olFolderInbox)
Set colItems = objFolder.Items
For Each objItem in colItems
'THE OUTLOOK ERROR MAY OCCUR HERE
TotalSize = TotalSize + objItem.Size
Next
Set objInbox = objNamespace.GetDefaultFolder(olFolderInbox)
GetSubfolders(objInbox)
msgbox "The size of Inbox and all Subfolders: " & Round((TotalSize / 1048576),2) & " MB"
End Sub
Sub GetSubfolders(objParentFolder)
Set colFolders = objParentFolder.Folders
For Each objFolder in colFolders
Set objSubfolder = objParentFolder.Folders(objFolder.Name)
intSize = 0
Set colItems = objSubfolder.Items
For Each objItem in colItems
'THE OUTLOOK ERROR MAY ALSO OCCUR HERE
intSize = intSize + objItem.size
next
TotalSize = TotalSize + intSize
GetSubfolders objSubfolder
Next
End Sub