boxed As on desktop

[marylaskow]

I received a box siting new updates for Mac OS X and iPod Nano and checked install. I received 2 launch failure messages "shared library error" and now on the text on my desktop and pull down menus has turned to boxed capital As.
What does this mean and how can I fix it? I can't read anything except on my internet browsers. I inserted my Tiger disc to try to reinstall, but the text on it also is the boxed As.
Thanks.

 

[symphonix]

Boot from the installer disk by holding "C" while you turn the computer on. You can then perform an "archive and install" which will back up your old files before re-installing the system.