Pages not showing in a thread

Hey everyone,
been looking for a solution some time but I can't find it.
So I thought, why not drop you a message here.

I have a thread (and it's probably not the only one like that) which has 6 pages. The default Display Mode is Linear.
I can access the first 3 pages of the thread. If I try to access the 4th or any other page it just sends me back to the 3rd page.
In Hybrid Display Mode I can view all the posts, but as I said, Linear is the default.

The vB version is 3.5.3 (we'll be doing an update soon, but I would like to resolve this before the update).

Thanks!

try the update first, and see if it corrects itself. My first guess is a corruption in the database.

OK, will try that and see how it goes.
Thanks!