I installed MarketPress eCommerce Lite and was able

I installed MarketPress eCommerce Lite and was able to setup the store easily with no issues, however, needed to be able to process with Authorize.net so I purchased the paid version. After purchasing the paid version it had me install another plugin (MarketPress) and when I enabled that plugin I had issues with the theme. The slider on the front page doesn't work, or the menu page when MarketPress is enabled. Works fine with MarketPress Lite, but I need Authorize.net to work. Wondering if you can assist.