Donation Button Not Processing on all Web Browsers

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Buttons are located in the header, footer, and throughout the site. Donations are not completing processing unless Firefox is used. Again, the button only works properly when using Firefox. Chrome and explorer are not working. Donations are being lost because of this. Please advise. http://gpeacefoundation.org/financial-donations/

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<form action="https://www.paypal.com/cgi-bin/webscr" method="post">
	<input name="cmd" value="_s-xclick" type="hidden"> <input name="hosted_button_id" value="KKMQFT4VLLEPY" type="hidden"> <input alt="PayPal - The safer, easier way to pay online!" name="submit" src="https://www.paypalobjects.com/en_US/i/btn/btn_donateCC_LG.gif" type="image" border="0"> <img alt="" src="https://www.paypalobjects.com/en_US/i/scr/pixel.gif" width="1" height="1" border="0"></form>

This is the code being used. Please advise. Thank you.