OK I am now using the following to return the file associations back to Media Player after installing ShowTime: If $RFA = 1 Then RegWrite ( "HKCR\.aif", "", "REG_SZ", "AIFFFile" ) RegWrite ( "HKCR\.aifc", "", "REG_SZ", "AIFFFile" ) RegWrite ( "HKCR\.aiff", "", "REG_SZ", "AIFFFile" ) RegWrite ( "HKCR\.avi", "", "REG_SZ", "avifile" ) RegWrite ( "HKCR\.m1v", "", "REG_SZ", "mpegfile" ) RegWrite ( "HKCR\.m3u", "", "REG_SZ", "m3ufile" ) RegWrite ( "HKCR\.mid", "", "REG_SZ", "midfile" ) RegWrite ( "HKCR\.midi", "", "REG_SZ", "midfile" ) RegWrite ( "HKCR\.mp2", "", "REG_SZ", "mpegfile" ) RegWrite ( "HKCR\.mp3", "", "REG_SZ", "mp3file" ) RegWrite ( "HKCR\.mpa", "", "REG_SZ", "mpegfile" ) RegWrite ( "HKCR\.mpeg", "", "REG_SZ", "mpegfile" ) RegWrite ( "HKCR\.mpg", "", "REG_SZ", "mpegfile" ) RegWrite ( "HKCR\.rmi", "", "REG_SZ", "midfile" ) RegWrite ( "HKCR\.wav", "", "REG_SZ", "soundrec" ) RegWrite ( "HKCR\.wma", "", "REG_SZ", "WMAFile" ) RegWrite ( "HKCR\.wmv", "", "REG_SZ", "WMVFile" ) EndIf I have also extracted the main setup executable so this doesn't have to be done during the install. This makes the process much faster, means that the Ask Toolbar installer can be deleted completely and hopefully the DirectX update issue will be avoided. My final script is now quite different to CEoCEo's, but many thanks for introducing me to the wonderful world of AutoIt and setting me off in the right direction.