just wanted to report an issue (i got it to work via sql, but it would be good to fix it eventually)
I am running wpmu 2.8.3 + atahualpa 3.4.2

The Theme options that store PHP code and html bits (17 in total, list below) somehow got their values scrambled (a slash was added to escape quotes + other things). This made the central (content) panel go blank (the side bars continued to work). I did some digging and found for example for option bfa_ata_content_not_found

INSTEAD of
"<h2><?php _e('Not Found','atahualpa'); ?></h2>
<p><?php _e(""Sorry, but you are looking for something that isn't here."",""atahualpa""); ?></p>"

the wp_options table had (see the slashes?):

"<h2><?php _e(\'Not Found\',\'atahualpa\'); ?></h2>
<p><?php _e(\""Sorry, but you are looking for something that isn\'t here.\"",\""atahualpa\""); ?></p>"

The complete list of options that had their values scrambled:

'bfa_ata_custom_read_more',
'bfa_ata_html_inserts_body_bottom',
'bfa_ata_content_above_loop',
'bfa_ata_content_inside_loop',
'bfa_ata_content_below_loop',
'bfa_ata_content_not_found',
'bfa_ata_footer_style_content',
'bfa_ata_more_tag',
'bfa_ata_multi_next_prev_newer',
'bfa_ata_multi_next_prev_older',
'bfa_ata_single_next_prev_newer',
'bfa_ata_single_next_prev_older',
'bfa_ata_comments_next_prev_newer',
'bfa_ata_comments_next_prev_older',
'bfa_ata_post_footer_home',
'bfa_ata_post_footer_multi',
'bfa_ata_post_footer_single'

I had a backup and restored the values. The central panel started showing pages and posts again.

it looks like you must have set the backslash as your escape character

thanks for the tip. Is the escape character a WP or atahualpa option?
The slash wasn't the only thing that got added though. The copyright character was replaced with &copy; as were all the other special characters. I don't think they were the reason for the blank page - the slash was probably the culprit.
I found a similar issue on this forum
http://forum.bytesforall.com/showthread.php?t=20

Try adding this to your .htaccess

php_flag magic_quotes_gpc off