tedster - 4:20 pm on Jul 21, 2006 (gmt 0)

Concise and descriptive alt attributes are not likley to cause what you've described, but it can do little harm to revert if you feel it might be playing in.

First thing to acknowledge is that Google sometimes makes mistakes. Also sometimes things happen mysteriously and then go away just as mysteriously. In addition to these possibilities, completely out of our control, you can go over your site for any technical issues that might have just begun to show their effects. Here are some threads that are worth a close reading:

Checklist for Sudden Drops in Rank [webmasterworld.com]
Dropped from Google - a checklist to find out why [webmasterworld.com]
Dropped Site Checklist [webmasterworld.com]
The url-only problem [webmasterworld.com]