2003, 2007 up to date

In VBE editor I have line-items in the drop down box Available References: that are missing.

I do not mean invalid or missing Checked items but invalid line items in the dropdown box.

i.e. There is a item listed as CT - Math.

If I select it, then OK; I get "Error in loading DLL" That is true because it was deleted.

How can I delete that and other like items.

TIA EagleOne