Gave me trouble for a while too. Here's what I ultimately had to do. I cleared cookies/cache, logged in at g.e-hentai.org
using "sauceguides" as the username and password (I couldn't get it to confirm my own registration at the time no matter how much I tried, maybe it's working now), and from there went DIRECTLY to exhentai in the same tab. Going in another tab/window might or might not be the cause of the problems I had. I am not sure how much of this matters and how much is just superstition, I'm just trying to be very specific in the steps that worked for me when I had the same trouble.
Insert snippy comment implying my superiority to you for having looked at pornography by these means for longer than you have here.