I need to automatically scroll down all items in a web page drop down box

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VB

I am currently using the SendKeys as below:(VB.Net)
SendKeys.Send("^{DOWN}") 'Scroll down
SendKeys.SendWait("-1") 'Wait until sendkey has completed

The problem that I have is,while my software project is running (scrolling through the web page drop down list) I am unable to use any other app on my desktop.

Example:
When I use Excel or notepad,it will keep entering -1-1-1-1-1 continuously, until I click on my projects form.
This is driving me mad,and would love to find a way to scroll through each item in a web page drop down list while using another app at the same time.

What I have tried:

I have tried to prevent the cursor from leaving the form,but people that use my software,dont like to be restricted in this way.