Hello Maarten and welcome to the board.

Please let us know the following information to better help you.

1. What network type do you have NT or AD
2. What client types do you need to support 9x/NT/2K/XP
3. What version of KiXtart are you using

Here is some example code you can try. Copy the following code to a text file then run from a DOS Console KIX32.EXE NEWFILE.KIX and it should operate for you.

I'm not sure what or where you are defining your variables so I created these to demonstrate their operation. If you have real values for them then you can plug those in as well in the real script. For now, just to demonstrate simply run the code as is below.

Code:
Break On
$nul=SetOption('Explicit','On')
$nul=SetOption('NoVarsInStrings','On')
Dim $DriveI,$DriveJ,$DriveK,$DriveL,$DriveM,$WelkomMSG

;welkoms scherm;--------------------------------------------
$DriveI = 'I: '
$DriveJ = 'J: '
$DriveK = 'K: '
$DriveL = 'L: '
$DriveM = 'M: '

$WelkomMSG = 'Greetings ' + @FullName
+ @CRLF + 'Welkom Op het netwerk van: MAAN '
+ @CRLF + 'De volgende netwerkschijven zijn verbonden: '
+ @CRLF + $DriveI
+ @CRLF + $DriveJ
+ @CRLF + $DriveK
+ @CRLF + $DriveL
+ @CRLF + $DriveM
$WelkomMSG = MessageBox($WelkomMSG,'Login Script',64)