Filebase Internal server error

Hello!
I am using Filebase for some time now, I and installed it on several sites. It always worked, and I newer encountered any kind of problem.
On last site, whenever I try to call FB, pop-up with “Internal server error ” jumps out, and server error log shows following:
[Wed Oct 17 21:20:32 2012] [error] [client 66.249.66.80] File does not exist: /home/imsi/public_html/404.shtml
[Wed Oct 17 21:20:32 2012] [error] [client 66.249.66.80] File does not exist: /home/imsi/public_html/imsiportal/files/aplikacije/organizacija/referati/arhiva_referata/http:
[Wed Oct 17 21:20:22 2012] [error] [client 178.222.111.112] File does not exist: /home/imsi/public_html/500.shtml, referer: http://imsi.rs/imsiwp/wp-admin/post.php?post=1592&action=edit
[Wed Oct 17 21:20:22 2012] [error] [client 178.222.111.112] SoftException in Application.cpp:601: Directory “/home/imsi/public_html/imsiwp/wp-content/plugins” is writeable by group, referer: http://imsi.rs/imsiwp/wp-admin/post.php?post=1592&action=edit
[Wed Oct 17 21:20:16 2012] [error] [client 178.222.111.112] File does not exist: /home/imsi/public_html/500.shtml, referer: http://imsi.rs/imsiwp/wp-admin/post.php?post=1592&action=edit
[Wed Oct 17 21:20:16 2012] [error] [client 178.222.111.112] SoftException in Application.cpp:601: Directory “/home/imsi/public_html/imsiwp/wp-content/plugins” is writeable by group, referer: http://imsi.rs/imsiwp/wp-admin/post.php?post=1592&action=edit
[Wed Oct 17 21:20:12 2012] [error] [client 178.222.111.112] File does not exist: /home/imsi/public_html/500.shtml, referer: http://imsi.rs/imsiwp/wp-admin/edit.php?post_type=page
[Wed Oct 17 21:20:12 2012] [error] [client 178.222.111.112] SoftException in Application.cpp:601: Directory “/home/imsi/public_html/imsiwp/wp-content/plugins” is writeable by group, referer: http://imsi.rs/imsiwp/wp-admin/edit.php?post_type=page
[Wed Oct 17 21:20:05 2012] [error] [client 178.222.111.112] File does not exist: /home/imsi/public_html/500.shtml, referer: http://imsi.rs/imsiwp/wp-admin/about.php?updated