Apple finally rolled out ‘iOS 5′ its most awaited operating system for idevices like iPhone 3GS, iPhone 4, iPod Touch 3G, iPod Touch 4G, iPad and iPad 2. I heared that people are getting so many errors while updating to iOS 5 like ‘An unknown internal error occurred’.
Well there is a single solution for most of them problems which is,
> Keep your Internet Explorer up to date (Because of the fact that iTunes uses IE service for downloading and uploading)
> Turn off your Anti-virus and Firewall completely
The above solution may not be the ultimate one, but it solves most of your errors. Lets me know how much it helped you
Still facing issues while updating to iOS 5, Well this alternative may helps you.