Module development and code questions

Hi,

Recentyly I have encountered a strange problem. After adding a new own built module I got this warning.

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warning: Cannot modify header information - headers already sent by (output started at D:\Usr\WWW\Drupal\modules\advert\advert.module:1) in D:\Usr\WWW\Drupal\includes\common.inc on line 266.
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I can add remove and edit content but after hitting submitt i got a blank page. When I navigate back in a browser I can actually see changes were applied (plus i got a warning message). This scenario is applicable to any content of my site. When I administer site as an administrator and apply some settings or I act as an user trying to log on. Every time the same sheme submit, blank page, navigate back, changes were applied.

When I remove module from \modules folder everything gets back to normal.

I have tried to comment separate functions to track down one which is responsible for this problem.
Without any success. Only removal of module is effective.

Module is responsible for storing content about advertisements, here is a list of module functions:

function advert_help($section) {}
function advert_access($op, $advertisement) {}
function advert_menu($may_cache) {}
function advert_form(&$advertisement) {}
function advert_validate(&$advertisement) {}
function advert_insert($advertisement) {}
function advert_nodeapi(&$advertisement, $op, $teaser, $page) {}

Whenever I try to create an image using the image module, I get the following error:

Unable to create thumbnail image
The selected file /home/x3oadmin/public_html/gaming1/files could not be copied.

Any help or advice?

I am wondering whether I can build 2 categories with certain relationships. Let's say the list in the 1st category contains terms 1,2,3,4,5,6... and the list in the 2nd category contains terms A, B, C, D, E, F, G, H, I, J... Term 1 is related to C, D, E. Term 2 is related to A,B,C. Term 3 is related to I, J, and so on. When a user select term 1 in the 1st category, the list in the 2nd category should only display C,D,E for the user to select.

So far, I have not found any solutions among existing modules. Does anybody have any ideas.

Hi,
I'm looking for a way to have an article which can be commented.
It's comments are shown in a list of titles (sort of a preview).
When the title is a JS link that expands the comment to show its content...

how can I do this?

Hello
i want to display limited images on any page and giving linking to other pages i.e i want to display 20-25 images per page and give links to them

Does anyone know if the Organic Group List Manager works with Google For Your Domain (GFYD)?

Here's more info on GFYD.