Text widget overriding other sidebar widgets

On my website (www.wpspandc.com.au) which uses the Pinboard theme, I am using the Sidebar on the homepage, which contains my latest posts (i.e. is not a static page).

I have created a Text Widget for our sponsor (a local real estate agent) and inserted it in the Sidebar Top. Clicking on the McGrath logo in my Text Widget takes you to the McGrath website.

However, I’m finding that clicking on ALL other items in the sidebar (like “Your Shopping Cart” or the “Subscribe” button) also take you to the McGrath website, instead of to where it should. If you hover the mouse over the other sidebar widgets, you can see the McGrath URL as the target URL.

Is this a problem with the widget, or the theme???

FYI, my Text Widget is as follows (and sits at the top of the ‘Sidebar Top’ above 2 other plugin widgets):

Proudly Sponsored by by John McManus and Adam Wong of McGrath Real Estate