Hi,
Since a few weeks ago I'm getting this weird error on my logs:
warning page not found 17 Jan 2007 - 13:13 internal_error.html not found. (Anonymous or any user)
I have realized when this happens, instead of showing a page Drupal shows only a "Page not found" error.
This is happening on peak hours, when my server has more traffic. But this traffic is not that much (maybe 10-15 users and 20-30 guests).
I have a good package on DreamHost and I have been talking with them too about this issue. I don't think it is a problem of CPU, server load neither bandwith.
Doing a top on my server on prime time (peak hours) I can see a lot of simultaneous php processes running. What is weird is than some of them are labeled as "defunct", which to me means that request wasn't completed, maybe DB connection was lost or something like that.
I have to say all this started after setting up different modules like OG, Views, Actions and Vote Up/Down. I have read about the incompatibilities between locale and OG, so I have deactivated locale module meanwhile.
On my prevous hosting I had some issues when users where posting comments, with pages staying in blank. This was making users to refresh page which caused comments to get duplicated. This didn't happen very often but was one of the reasons I shwitched to DreamHost.
But now I think the problem is worst.