The answer is directly in the error message. You need to assign the IP address of the second computer in the script.

Line 44 in C:\Users\*name*\Documents\hotkeynet_210\Script 1.txt: <SendLabel w2>
you must specify an IP for <Hotkey ScrollLockOn 0> with SendLabel or SendPC
Code:
//-----------------------------------------------------------
// HOTKEY TO LAUNCH BOTH WOW'S.
//-----------------------------------------------------------
<Hotkey ScrollLockOn Alt Ctrl L>
    <Launch Local>
    <Launch IP_ADDRESS_2>
Line 53 in C:\Users\*name*\Documents\hotkeynet_210\Script 1.txt: <SendLabel w2>
"w2" has not been defined as the name of a label.
you must specify an IP for <Hotkey ScrollLockOn A> with SendLabel or SendPC.
Line 66 in C:\Users\*name*Documents\hotkeynet_210\Script 1.txt: <SendLabel w2>
"w2" has not been defined as the name of a label.
you must specify an IP for <Hotkey ScrollLockOn Oem3 LButton> with SendLabel or SendPC.
Code:
//-----------------------------------------------------------
// DEFINE MAIL LABELS FOR SENDING KEY STROKES 
//-----------------------------------------------------------
<Label w1 Local SendWin "World of Warcraft">
<Label w2 2ND_IP_ADDRESS SendWin "World of Warcraft">