Yep, same problem as BOAC, click on 'last page' and it takes me to 32 but shows 33 & 34 click on either, 32 reloads.
I -think- this is normal. On many threads, extra pages are preloaded because it's apparent they will be needed, but there's in fact nothing on them yet. As soon as posts spill over onto the next of those "extra pages," you'll be able to access it. The reason you try to open page 33 and 32 reloads is that there's nothing on page 33 yet.