where the login doesn't work, the first thing I would suspect is the servers session management, use the sesssionTest.php page from the following post to test the servers session management:
showpost.php?p=23826&postcount=2
The link you provided does not go to the store files, can you provide a more direct link where I could see the problems you are reporting, and also a link to the sessionTest.php file once it is uploaded.