"Expected end of line, etc. but found end of script." HELP!!

Question

When I try to run my script, it say "(null.)" When I try to compile it or save it as an application, it says "Expected end of line, etc. but found end of script." HELP!!!
Here is my script:
display dialog "WARNING! a virus has been detected and the system is crashing" buttons {"shut down computor to preserve contents", "burn virus file"} default button 2
if the button returned of the result is "burn virus file" then
say "warning the virus has reacted to its deletion and has activated itself"
say "virus is now in control of the users computor"
say "if you try to stop the virus it will delete all user data"
tell application "Safari"
activate
open location "http://www.facebook.com"
open location "http://www.yahoo.com"
open location "http://www.gmail.com"
open location "http://www.youtube.com"
end tell
tell application "iTunes"
activate
play
end tell
tell application "iCal"
activate
end tell
tell application "Terminal"
activate
end tell
tell application "Finder"
quit
end tell
if the button returned of the result is "shut down computor to preserve contents" then
say "your computor will shut to protect your files."
say "shut down in t-3"
say "2."
say "1."
say "goodbye"
say "it appears that there is a problem"
say "the virus is starting to take over your system"
beep 17
display dialog "how DARE you try to delete me. I am now going to take over your computer." buttons {"**** YOU GET OUTTA MY COMPUTER", "OK, have fun!!"} default button "OK, have fun!!"
if the button returned of the result is "OK, have fun!!" then
say "thank you!!"
say "watch this!"
Tell application "iChat"
quit
end tell
Tell application "Finder"
quit
end tell
if the button returned of the result is "**** YOU GET OUTTA MY COMPUTER" then
say "That attitude will not be tollerated."
say "Dum dum dum dum dum dum dum he he he ho ho ho fa lah lah lah lah lah lah fa lah full hoo hoo hoo" using "Cellos"
display dialog "A virus has been detected going through your files. Would you like to try to stop this?" buttons {"OK"} default button "OK"
if the button returned of the result is "OK" then
beep 5
display dialog "there has been an error. Do you want to try to force quit?" buttons "Yes" default button "Yes"
if the button returned of the result is "Yes" then
say "Well, thats just too bad!"
beep 2
say "Sorry about that."
say "The virus has been purged from your system."
say "Your computer will now restart to make sure that all traces of the virus have been removed."
say "shut down in t-3"
say "2"
say "1"
say "goodbye"
tell application "Finder"
restart
end tell
end if

Answer 1

You need to complete compound if statements with an end if - see the AppleScript Language Guide for a description of the various kinds of if statements.
Although I don't think it is going to do what you expect, your script would look something like:
<pre style="
font-family: Monaco, 'Courier New', Courier, monospace;
font-size: 10px;
font-weight: normal;
margin: 0px;
padding: 5px;
border: 1px solid #000000;
width: 720px; height: 340px;
color: #000000;
background-color: #DAFFB6;
overflow: auto;"
title="this text can be pasted into the AppleScript Editor">
display dialog "WARNING! a virus has been detected and the system is crashing" buttons {"shut down computor to preserve contents", "burn virus file"} default button 2
if the button returned of the result is "burn virus file" then
say "warning the virus has reacted to its deletion and has activated itself"
say "virus is now in control of the users computor"
say "if you try to stop the virus it will delete all user data"
tell application "Safari"
activate
open location "http://www.facebook.com"
open location "http://www.yahoo.com"
open location "http://www.gmail.com"
open location "http://www.youtube.com"
end tell
tell application "iTunes"
activate
play
end tell
tell application "iCal"
activate
end tell
tell application "Terminal"
activate
end tell
tell application "Finder"
quit
end tell
else if the button returned of the result is "shut down computor to preserve contents" then
say "your computor will shut to protect your files."
say "shut down in t-3"
say "2."
say "1."
say "goodbye"
say "it appears that there is a problem"
say "the virus is starting to take over your system"
beep 17
end if
display dialog "how DARE you try to delete me. I am now going to take over your computer." buttons {"**** YOU GET OUTTA MY COMPUTER", "OK, have fun!!"} default button "OK, have fun!!"
if the button returned of the result is "OK, have fun!!" then
say "thank you!!"
say "watch this!"
tell application "iChat"
quit
end tell
tell application "Finder"
quit
end tell
else if the button returned of the result is "**** YOU GET OUTTA MY COMPUTER" then
say "That attitude will not be tollerated."
say "Dum dum dum dum dum dum dum he he he ho ho ho fa lah lah lah lah lah lah fa lah full hoo hoo hoo" using "Cellos"
end if
display dialog "A virus has been detected going through your files. Would you like to try to stop this?" buttons {"OK"} default button "OK"
if the button returned of the result is "OK" then
beep 5
display dialog "there has been an error. Do you want to try to force quit?" buttons "Yes" default button "Yes"
else if the button returned of the result is "Yes" then
say "Well, thats just too bad!"
beep 2
say "Sorry about that."
say "The virus has been purged from your system."
say "Your computer will now restart to make sure that all traces of the virus have been removed."
say "shut down in t-3"
say "2"
say "1"
say "goodbye"
tell application "Finder"
restart
end tell
end if
</pre>