I'm using TsComboBox in several commercial applications without ever seeing anything like you describe so my suspicion is that you've either found some bizarre corner case or more likely your combo selection has an unintended side effect. Can you modify your code so that when the form is first displayed you don't manipulate the combo at all – that way you could test that the items were still there at the start at least. Another idea – if you replace your TsComboBox with a TComboBox do you get the same effect – if you do then you know it is your code at fault. If you are able to post code then I'd help you debug but I am quite sure that this will not turn out to be an AC control issue.
Yeah, thats the weird part, i'm using the TsCombobox in several other forms across the application (sometimes in combination with the treeview control) and it works fine in those forms, its only here, but let me remove any kind of code that accesses the combobox and I'll get back to you.
Okay yeah, for some strange reason, setting the item index to 3, cleared all the items, I removed all code that accessed the combobox and started adding back one line at a time, I uncommented a line to set the item index, it tried to set the value of 3 (which is well within range) but after a while all the items just disappeared :/. Looks like im gonna have to stick with the listbox for now. tre bizarre