438835 Quick Project For Virtuemart Expert

This is a simple project for a virtuemart expert. The problem I have is with the payment module. If I login the front-end of my site using my default admin Username, I can buy products with paypal, no problem. However all the other members trying to purchase products from the front-end experience problems at the checkout page. There is no value next to "Payment Method:". If they click "Confirm Order", they get this error message: "Error: Please select a Payment Method." But there is no Payment method to select. And besides, I dont want a payment method to be selectable, I just want PayPal to be the only option. If you are confident about virtuemart, then please bid My site specification at the moment is Joomla 1.5.15, Virtuemart 1.15 and aec.