Twice today my Moodle site has "hung up" for lack of a better word for 10-15 minutes. The error message on the home page shows "Could not find forum module!!" in two different places and the courses/categories will not load. During this time, it's incredible slow to allow login (if at all) although if I can get logged in as administrator, I can get to the individual classes and activities. Students during this time period can't access or log into new courses. The problem does seem to clear itself after a short period of time.
I'm using Moodle 1.6 (I must have activity locking) so upgrading is not likely an option). My database is around 95 MB, but I have my own dedicated server. (4 cores, 4MB RAM) My server load is really low so I'm just wondering if anyone has any suggestions or recommendations as to what could be causing the problem. The only time I find this same error message in the forums dealt with installation errors and that was a while back. My installation has been running well for about a year.