Unsolicited dropdown list from combo box

G'day Excel Forum

I’ve been following a method I found on the net for building a search bar with suggestions drop-down (like a Google search), described here; http://trumpexcel.com/tag/excel-search/

It’s worked quite well however I am having a small issue with it;

Weirdly whenever I click on any button, tick any check-box or hit enter after typing anything elsewhere in my sheet, the search suggestions box I’ve built using this method drops down (the attachment may make this clearer).

I’ve been discussing it with a very knowledgeable forum moderator while working on this worksheet however we’re both stumped.

Has anyone any idea why it might be doing this? Could it perhaps be clashing with another code or have something to do with the version of excel I'm using (2010)?

Would appreciate any insight you'd have

Regards

MattRNR

P.S. The helper columns and data can be found on the database sheet.