Are you still having this problem?
If so, just check the permissions under your Administrator account if your dads isn't on an administrator status.
If he is, then there shouldn't be any restrictions and you might want to go under your network settings in your control panel and see if when your logged in on it check to make sure your network adapter is enabled.
Let me know if you need any help checking this, also if there is anything else that you might think is the problem? New account? Might be best to Create new account and save his documents/etc. under your shared folder and just transfer it back to his account.
I've had similar problems with a Guest account except I just removed it due to not needed it really.