suddenly I'm getting a lot of "unable to..." errors on various files, mostly inside /usr/local/directadmin/data:
Unable to write session file: Unable to read session file: Unable to open /usr/local/directadmin/data/sessions/da_sess_.....
2012:04:18-10:10:08: Unable to write ./data/admin/login.hist: Unable to get Lock on file:<br>
open error for ./data/admin/login.hist.lock: Operation not permitted<br>
and many, many more...
I'm unable to login into that system with any admin.

please help.