still cant edit

I can't edit item 279865. I'd like to replace the thumbnail and every time I do so, it's replaced by the old image.

This happens on every item I try to replace images in my 'future members' (hidden) section.

Awesome! This will help me look into it. I'll try to gain some insight into why this is happening tomorrow. (Sunday)

If it helps to have another: http://www.rubberslug.com/member/gallery/item.aspx?id=116564

Same issue. I have a better screencap, but...
It lets me delete it... does an awesome fade to black, or gray rather, then lets me upload the new one "successful!", but... the old screencap stubbornly remains.
I can edit text in old posts, and add new pictures to previously empty slots in old posts, but cannot delete an old picture and upload a new one.

I tried to edit item 262260 tonight and the following message appeared -

An error occurred at 1/24/2011 8:06:06 PM as follows

Exception of type 'System.Web.HttpUnhandledException' was thrown.

at System.Web.UI.Page.HandleError(Exception e)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
at System.Web.UI.Page.ProcessRequest()
at System.Web.UI.Page.ProcessRequestWithNoAssert(HttpContext context)
at System.Web.UI.Page.ProcessRequest(HttpContext context)
at ASP.member_gallery_item_aspx.ProcessRequest(HttpContext context)
at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

---------------------------------

Invalid postback or callback argument. Event validation is enabled using in configuration or in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.

at System.Web.UI.ClientScriptManager.ValidateEvent(String uniqueId, String argument)
at System.Web.UI.Control.ValidateEvent(String uniqueID, String eventArgument)
at System.Web.UI.WebControls.DropDownList.LoadPostData(String postDataKey, NameValueCollection postCollection)
at System.Web.UI.WebControls.DropDownList.System.Web.UI.IPostBackDataHandler.LoadPostData(String postDataKey, NameValueCollection postCollection)
at System.Web.UI.Page.ProcessPostData(NameValueCollection postData, Boolean fBeforeLoad)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

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One more.
I deleted the item in sketch 3 (I think. By now I'm not sure anymore.), and uploaded a new screencap. But when I saved, the item in sketch 2 (actual sketch) is now gone?
By now, I'm wondering if I didn't just accidentally delete sketch 2, but I was so sure I'd deleted #3...

http://www.rubberslug.com/member/gallery/item.aspx?id=152318

(I wouldn't mention it but, I can't seem to find my saved scan of that sketch, to re-upload it.) (I may just have to dig out the sketch and take a photo...)