Very odd problem. I do have a larger database, with many myisam tables.
A couple days ago, some of them turned 'read only'.
Symptom:
delete from day_48392 where id=28398776259;
ERROR 1036 (HY000): Table 'day_48392' is read only
I checked:
- table file permissions are right ('660
Well, I found the reason for these table becoming 'read only':
These tables where part of a merge table, which included some read only
tables (read only set in file system).
Now even after the merge table was dropped, all member tables stayed
'read only' regardless of their individual file
