If you use the *hacked* version of gallery 3.1.11, you can find it on the gallery forums. it is posted by a user called AngelOnline.

The gallery wil still be broken, but it allows installation on DNN4.0.2 and the integration of the gallery with the forums. To add avatars to a galery, put the gallery module on a page, point it to the same filesystem location as the gallery used by the forums and manage your avatars with the gallery module (use the default settings for the gallery, everything else will kill your gallery/portal)

I have no idea how to fix attachments on DNN4.02 but i did manage to get a nice ASP.NET error page staing this:

Stack Trace:

[ArgumentNullException: Value cannot be null.
Parameter name: format]
   System.String.Format(IFormatProvider provider, String format, Object[] args) +2835599
   DotNetNuke.Modules.Forum.AttachmentFile.ValidationInfo(Config ForumConfig) +601
   DotNetNuke.Modules.Forum.AttachmentPage.AddFile() +106
   DotNetNuke.Modules.Forum.AttachmentPage.cmdAdd_Click(Object sender, EventArgs e) +58
   System.Web.UI.WebControls.LinkButton.OnClick(EventArgs e) +105
   System.Web.UI.WebControls.LinkButton.RaisePostBackEvent(String eventArgument) +107
   System.Web.UI.WebControls.LinkButton.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +7
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +11
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +174
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +5102

I didn't get any further then this. I'l be looking into it this weekend

I can confirm ATTACHMENTS DO NOT WORK on DNN 4.0.2 due to multiple bugs, some of them can not be fixed without recompiling the forums.

Guys, I don't believe it's this is a 100% Gallery issue.  The code to upload some items like "Avatar" is in the forum's code.  (See my post here:  http://dotnetnuke.com/Community/ForumsDotNetNuke/tabid/795/forumid/7/threadid/28826/scope/posts/Default.aspx)

I've found the code for the updates but can't debug to follow if the txtAvatar.Text value gets passed as the Actual text value or if a null is getting passed by accident.