Help: Forum Page Outage

This concerns

Forum software: Invision Power Board 1.3.1(final)

This forum has been up and running for months - error free!

I come in this morning and I’m getting certain “This page cannot
display” errors in the forums. Some pages display fine - some give
me that error?

I am also getting this same error in the Admin CP for the forums.

I checked all the files in the directory and nothing is missing.

I tried to backup the DB and I believe
it worked correctly, but Im unsure if it is 0 correct.

I’ve posted this issue in the Community help forum
and all sources say “check with your host”.

Please help me out on this - I have taken the board “offline” but is
still accesable to admin’s.

One other weird thing is… I click on some pages - they display - then refresh - I get the error - click on it later - it displays again??? What the heck is that all about?