Code:
So each day it selects a new line, so when one user logs on Tuesday, they see the selection for Tuesday, along with any other user that logs on that day?


This doesn't sound like a requirement for random results to me, it sounds more like you just want a new message each day.

If this is the case, use an INI file to record the message for the day.

You need two entries in the file - one is the cureent message number and the other is the date that the message was used. If the date <> today, add two to the message counter (wrap to zero when you reach the end of the file) and set the used day to today.

Here is an example (untested):
Code:
Break ON
$=SetOption("Explicit","ON")
Dim $sIni,$sMOTD,$fhMOTD,$asData,$sRecord,$sUsedDay,$iMessage
 
; If the INI file does not exist it will be created
$sINI=@SCRIPTDIR+'\MessageOfTheDay.ini'
; MOTD file contains all the empowering messages
$sMOTD=@SCRIPTDIR+'\MessageOfTheDay.txt'
 
$fhMOTD=FreeFileHandle()
If @ERROR
	"Cannot allocate a free file handle [" +@ERROR+"] "+@SERROR ?
Else
	If Open($fhMOTD,$sMOTD)
		"Cannot open message file for reading ["+@ERROR+"] "+@SERROR ?
	Else
		$sRecord=readline($fhMOTD)
		While Not @ERROR
			$asData=$asData+$sRecord+Chr(10)
			$sRecord=readline($fhMOTD)
		Loop
		$=Close($fhMOTD)
		$asData=Split(Left($asData,-1),Chr(10))
		$sUsedDay=ReadProfileString($sINI,"CONTROL","LastUsed")
		$iMessage=Val(ReadProfileString($sINI,"CONTROL","Message"))
		If $sUsedDay="" $sUsedDay=@DATE EndIf
		If $sUsedDay<>@DATE
			$iMessage=$iMessage+2
			If $iMessage>=UBound($asData) $iMessage=0 EndIf
			$=WriteProfileString($sINI,"CONTROL","LastUsed",@DATE)
			$=WriteProfileString($sINI,"CONTROL","Message",$iMessage)
		EndIf
		">> "+$asData[$iMessage] ?
		">> "+$asData[$iMessage+1] ?
	EndIf
EndIf


You will need to ensure that your users can write to the INI file during logon.