Error 905 is related to the store application used by Google. From what I understand, it seems that your version of the market is outdated and you need to upgrade it in order to get rid of the persistent error. I would suggest adding another Google/Gmail account and test if you get the same error. Another solution I discovered when this error was quite frequent was to clear the DALVIK CACHE that is accessible by going into the
Recovery menu of your mobile phone.
In order to get updated, you should first open your market application, go to
Settings and check "Automatically update applications". Then perform a reboot of your device and connect to Internet. It is advised that you should browse through the market application while the new software is downloaded and next time you start the application it will be updated to the last version.