AppleScript Editor Error - "Can't get document 1. Invalid index"

Try putting in a delay after opening the file.

 

Red Menace is absolutly right, several problem Applescript posts recently, have not taken into account, that Applescript is a slow language, and applications need time time to react to its requests, so always use the delay command, this allows the scriotable application time to react to the commands.

I have rewritten your script, so try this version, it seems to work OK, but I hav'nt tried it on a restart, so if you have problems with it on a restart, I'll rewrite again for you.

Code:

tell application "QuickTime Player"
	activate
	try
		set movieFile to ((path to movies folder) & "Dancer.mov" as text) as alias
	on error errorMsg number errorNum
		display alert errorMsg & space & errorNum message ¬
			"An error occured trying to find the file " & movieFile & "." & return & ¬
			"Check the file path exists, and the file spelling." as warning giving up after 60
	end try
	try
		open movieFile with presenting
		delay (0.25)
		present document 1
		delay (0.25)
		set looping of document 1 to true
		play document 1 with looping
	on error errorMsg number errorNum
		display alert errorMsg & space & errorNum message ¬
			"An error occured trying to open & play the file " & movieFile & "." & return & ¬
			"Check the file path exists, and the set delay time" as warning giving up after 60
	end try
end tell

Also I have used the path to a movie file on my system, but you will have to change the line.

Code:

set movieFile to ((path to movies folder) & "Dancer.mov" as text) as alias

To point to the file you want on your system.

Hope this helps.

Regards Mark