I was having the version of itunes 10.3 in my pc and wanted to update to itunes 10.5?

[inorange]

i updated it but when i tried to open itunes then, an error occured that entry point not found
'"VTSelectAndCreateVideoDecoderInstanc? could not be located i the dynamic link library videotoolbar.ddl""

and then it shows
itunes was not installed correctly. plz reinstall it
i have reinstalled but nothig happened
what to do?