ok, so here's what's happening - and unfortunately this has been the case since version 4.4.2 so a little surprised as to why this didn't bubble up before this.
The subject value is being stored in the module settings instead of the List ID - in the case of the categories, the ID is being stored correctly and is translated correctly on the feedback form or in the view comments.
When I was doing the testing, I was creating lists for subjects like
Name: Test 1
Value: 1
Name: Test 2
Value: 2
If you do create subjects like this - you will not get an error even if you hide or show the subject field.
However in the case of the examples you guys have provided, it is obvious that you are setting the values as some text values too. In this case, the module was trying to load the correct List ID by converting the string into a number and trying to load that list item. This resulted in the error.
Solution:
There is one line of code that needs to be changed in settings.ascx.vb (go to line 104)
Change
.cboSubject.DataValueField = "ListValue"
to
Me.cboSubject.DataValueField = "ListID"
Recompile the module once the changes have been made and your error should now go away plus the correct subject is sent in the email generated. I apologize for the problems this has caused and take 100% of responsiblity for this particular issue.
I would like to issue a 4.4.4 release to address this issue and can still do so but do not expect that to be released within the next couple of days which will obviously not work for you guys. Additionally I've already converted all of the code for 5.0.0 and am getting ready to send that out for beta testing shortly and would prefer if this fix can be included as part of that fix. Towards that end, I can do the following
a) provide a link for the updated dll which simply needs to be replaced in the bin folder to solve this issue.
b) send over the fixed dll to anyone who needs it via an email.
Again, my apologies for the problems this has caused and please feel free to send me an email if you need the modified version of the dll. Once I make this post, I am going to try and see if I can upload the revised dll on dotnetnuke.com itself, otherwise I will find some alternative location to host the file for users to download. (Will provide the link once I can figure out where it should reside)..
Sanjay