Hi
In the Validate_Fields() Function change:

If Not Weekday(Range("B7").Value) = vbMonday Then
MsgBox "Start Date must be a Monday (week beginning)", vbInformation

to

If Not Weekday(Range("B7").Value) = vbMonday Or vbTuesday Or vbWednesday Or vbThursday Or vbFriday Then
MsgBox "Start Date must be a Weekday", vbInformation

I think this will give you what you want. I am unable to step through the code because there are missing sheets.

Hope this helps.
Good luck.
Tony(OTPM)