White Page with strange promption : when trying to add content to panel

Hi,

I am using ctools 6.x-1.5, panels 6.x-3.5.

I created a custom page with a panel layout, when I tried to add content, strange things happened sometimes:

1) When I tried to add custom content, and clicked finish button, the process seemed endless(always being with waiting status)

2) Sometimes when I try to add content to panel, it leads to a blank page with following output(tons of text, I only copied a little part):

[ { "command": "css_files", "argument": [ { "file": "/drupal-6.8/modules/aggregator/aggregator.css?C", "media": "all" }, { "file": "/drupal-6.8/modules/node/node.css?C", "media": "all" }, { "file": "/drupal-6.8/modules/poll/poll.css?C", "media": "all" }, ....

3) I have warning like this:

user warning: Data too long for column 'referer' at row 1 query: INSERT INTO watchdog (uid, type, message, variables, severity, link, location, referer, hostname, timestamp) VALUES (1, 'content', 'Panels: saved display with id %did', 'a:1:{s:4:\"%did\";s:1:\"2\";}', 5, '', 'http://127.0.0.1/drupal-6.8/?q=admin/build/pages/edit/page-panelpagetest', 'http://127.0.0.1/drupal-6.8/?q=admin/build/pages/nojs/operation/page-panelpagetest/handlers/page_panelpagetest_panel_context/content', '127.0.0.1', 1275287110) in C:\www\drupal-6.8\modules\dblog\dblog.module on line 144.

Any ideas why? Thanks a lot!

Hang