add menu_rebuild() in hook install

I'm not sure the menu is the cause of the problem. I do have a menu item now for "Create node or nodes via bulk upload", going to /advupload. On that page is a link to "Bulk upload files for node type 'Image gallery entry - single image' (For each file add it's new node)", going to /advupload/advimage_multinode. Following that link leads to a "Page not found" error.

I did go to the settings and save it again. It made no difference.

I'm not sure why you're referring to the menu. I don't think that's the problem.

It's that the secondary link to the /advupload/advimage_multinode page fails, returning a "Page not found" error. How is this page supposed to get created? Is there code building it somewhere?

I had a developer look into this further, and he found that the problem was somehow related to having the xml_sitemap_node module also enabled. Could you check into this conflict?

Your module conflicts with another. Instead of insulting us, you could be pleased that someone else took the time to test and identify an issue. We won't be the only ones who run into this.

The corrections required are to initialize $form_state as an array:

1) in advimage_up.module, before calling drupal_prepare_form, add this line (e.g at line 13):
$form_state = array();

2) in advimage_og.handlers.inc (in function advimage_og_prepare_node_fieldset), before calling _advimage_og_form_add_og_audience, add this line (e.g. at line 96):
$form_state = array();

It's a nice module you've shared. However most module maintainers are grateful for issues being reported and take an interest in finding the cause (after all, they know the code better than anyone and by sharing their module presumably intend to be helpful to others). If you want people to use it, the negative attitude shown by some of your comments will not help -- they come across as insulting and not in the spirit of the Drupal community.