44394 ZENCART FIXING EXPERTS ONLY

My online customized zen cart e-commerce store was recently upgraded to the latest version, unfortunatley since it was upgraded alot of buyers are having problems using the cart and logging in, Especially when using a AOL broweser once at the login page they are unable to leave, any page they want to go to they just get the login page, and another common problem is that once customers login they are able to browse the site but they are unable to checkout etc etc.. I need someone who can fix this quickly and properly, Only apply for this project if you really know what you are doing, I do not want to have to get this fixed more then 1 time. thank you.