User cant modifiy the files after installed?

I have compared two files and stored mismatched values in the temporary file.After that read the values from temporary file and replaced in original file.
I have used following code

page custom twofilecompare
page custom originalwrite
Function twofilecompare
FileOpen $0 "$INSTDIR\backup.properties" "r"
FileOpen $1 "$INSTDIR\orginal.properties" "r"
FileOpen $R0 "$INSTDIR\temp.properties" "w"
ClearErrors

loop:
FileRead $0 $2
${If} $2 == "$\r$\n"
Goto loop
${EndIf}
FindClose $0


FileRead $1 $3
IfErrors done
strcmp $2 $3 loop here
here:
FileWrite $R0 $2
Goto loop

done:
FileClose $0
FileClose $1
FileClose $R0
FunctionEnd

Function originalwrite
IfFileExists "$INSTDIR\temp.properties" 0 filenotfound
FileOpen $0 "$INSTDIR\temp.properties" "r"
loop:
FileRead $0 $1
IfErrors done
//do some stuff

done:
FileClose $0
Delete /REBOOTOK "$INSTDIR\temp.properties"
filenotfound:
MessageBox MB_OK "file not found"
FunctionEnd


After installed I cant edit original and backup property file.If i try to modify a prompt box display as
"please check if this file opened another program".But i have closed all files.
How to find file is closed or not ?
How to solve this problem?

You've got FindClose $0 in there - I'm guessing that should be FileClose?

Stu

Thanks.but i think no need for Findclose or Fileclose in that place.beacause i have closed all files in done section.

Yes, I was thinking the same thing.

Are you sure you've closed all open files? Try putting a messagebox after the fileopen commands, echoing the handles in $0 $1 and $R0. Then when you close them, put the same messagebox and check whether those registers still contain the same file handles. Maybe you accidentally changed the registers somewhere..