Deactivate your anti-virus and any other security program when doing the backup. Run the backup as an Administrator. Remove compressed files from the Backup selection. Do not backup anything but your C:\ drive
Under your Administrator account, get full rights and take ownership of the entire C:\ drive using the following procedures. If you can't do some folders, skip them an do as many of them as you can.
To see your permissions, right click the folder/file, click on properties, and check out the security tab. Check to see what permissions you have by clicking on your username (or user group). Here are the types of permissions you can have: http://windows.microsoft.com/en-US/windows-vista/What-are-permissions.
You need to be an administrator or the owner to change permissions (and sometimes being an administrator or even an owner isn't enough - there are ways to block even them from access (though a smart administrator knows these ways and can get around them - but usually shouldn't because they were denied access usually for a very good reason).
Here's how to change folder permissions in Vista: http://www.online-tech-tips.com/windows-vista/set-file-folder-permissions-vista/. To add take and grant full right permissions and ownership to the right click menu (which will make it faster to get in once it is set up), check out the following article: http://www.mydigitallife.info/2009/05/21/take-and-grant-full-control-permissions-and-ownership-in-windows-7-or-vista-right-click-menu/.
To fix this problem with the folders, take ownership of the folders or the drive (as an administrator) and give yourself full rights. Right click the folder/drive, click on properties, go to the security tab and click on Advanced and then click on the Owner tab. Click edit and then click the name of the person you want to give ownership to (you may need to add it if it isn't there - or it may be yourself). If you want it to apply to sub-folders and files within that folder/drive, then check the box for replace owner on sub-containers and objects and click OK. Back out and now there's a new owner for the folders/drive and files who can change permissions as needed.
Here's more information on taking ownership of a file or folder: http://www.vistax64.com/tutorials/67717-take-ownership-file.html. To add take ownership to the right click menu (which will make it faster to get in once it is set up), check out the following article: http://www.howtogeek.com/howto/windows-vista/add-take-ownership-to-explorer-right-click-menu-in-vista/.
I hope this helps.