Trouble accessing secure website

I recently installed an NT 4.0 workstation for a user with IE 5.5/128 bit encryption. This user now cannot access any secure site. She is a purchasing rep and needs access to secure sites that her employer requires. I’ve set the suggested security attributes, however, she can logon to another machine and gain access to her site without a hitch. I removed all of her cookies and reinstalled the latest SP. Any suggestions?