Sluggy Freelance is borked.
The website mentions that they're undergoing an archive glitch that causes it sometimes display the wrong page when you hit the next button. However, when using the site normally, that can be fixed by hitting the "refresh" button. When using this site, it skips ahead three years and stays that way. Refreshing doesn't help. I imagine that something happened when Comic Rocket was viewing the page for the first time, and then that glitch was preserved by the program.
For me, at least, it happens at page 243 - 244.
This is likely something that needs to be emailed to them directly, as i sounds like a bug. However it is worth noting that I have been reading the early pages of sluggy and haven't noticed this problem yet.