Issues with huge forum and huge threads

[محروم.كوم]

Hi

I have a weird problem on one of the forums I administer.

First, users report that a specific thread has gone missing, sometimes they still find it, but when they want to access it, they see the error message "No thread specified, please contact an administrator"
Other users can see the thread just fine and can access it normally.

Then I occasionally (and right now) find some kind of temporary tables in my phpmyadmin: aaggregate_temp_1341789000, taggregate_temp_1348826160 and so on. (4 at the moment)
This makes me believe that somehow a scheduled job didn't run properly? I discovered some memory exeeding related errors with the cron.php, apparently it has been cancled at some point. Maybe this has something to do with it?

- vb version: 3.8.5
- The thread in question has 69507 replys at the moment
- We're using custom-designed mods, all of those have been checked and not a single one does interfere with the thread/post system in any way
- The system has been unmodified for a few weeks, the problem appeared last week

Anyone has an idea where to look for the problem?

And: What are those temporary tables and can we delete them manually? __DEFINE_LIKE_SHARE__