Q. I am having trouble with Time Capsule and I don’t think that it is backing up. I get an error saying that the back up disk image could not be mounted. How can I fix this?

A. Time Capsule, as you may know, is an additional tool to help users back up their Macintoshes wirelessly over a local network. Users running Mac OS X 10.5 aka Leopard, can take advantage of the new easy to use back up feature Time Machine. That way they can protect their valuable data in case some disaster strickes their computer.

Time Machine and Time Capsule will back up data every hour that the Macintosh computer is up and running. Initially it does a complete backup and then in tracks and backs up any changed files. With the back you can recover a file or the entire computer’s system and data if either is lost somehow.

Some users have experienced similar problems with the initial versions of the Time Machine. For every Mac that it backs up it creates an image of the hard drive in the form of a sparse disk image. A disk image is a file that behaves like a removable hard drive and a sparse one doesn’t have a fixed size so it can grow as required. For some reason, the sparse image may get damaged – afterwards it may not be able to mount normally, so that it can be read from or written to.

The fix for this is simple. Your Time Capsule should appear in the Finder’s Side Bar. Open a new Finder window if one is not open. If you don’t see the sidebar click the white lozenge in the top right corner of the window. Open the Time Capsule’s drive where you will see one or more “sparsebundle” files. Look for the one that matches your computer’s name along with a jumble of letters and numbers. My computer’s Time Machine file is named “macbook_001b639842a7.sparsebundle”. The jumble represents you “Ethernet Address”, which you can find under Network in System Preferences.

To fix the problem – simply rename the file by changing a few letters or numbers. The next time that the Time Capsule backs your Mac up it will see the file is missing and it will create a new one. After a few days of successful back up you can delete the older back up file.

Q. I have two versions of the same program installed and I need to use the older version to open the files. I’ve tried to set the default in the Finder but it always seems to open the newer version.

A. While you can select a file in the Finder and choose “Get Info”. Then set the default application to open a file, your Mac may open the wrong applications that you have double-clicked. In the pre-Mac OS X days, your Macintosh would open the legacy file based on the “Creator” code in the Resource fork, which was used to store file resources such as a finder icon or image preview. Mac OS X has done away with the Resource Fork for compatibility reasons.

Without the application’s “creator” code, your Mac may have no idea what program should open the file. Like Windows and Unix systems, the Finder now uses the “dot file extension” in the file name to determine the file:application relationship. The Finder stores this information in it’s “com.apple.LaunchServices.plist” file. If you cannot set the default application, this “plist” may be corrupt. To fix it, Trash the file and the Finder will create a new one with the default relationships. However some applications such as those from Adobe, Microsoft and Quark will always tend open with the highest installed version. So dragging and dropping on the dock icon or choosing “Open With” from the contextual menu may be only way to control the behavior.