Multiple Plesk login attempts from localhost

[AlanRo]

Access log for Plesk shows multiple login attempts. This is also resulting in sw-engine-cgi running multiple instances throughout the day using 10-30% of the CPU.

[28/Apr/2012:21:58:41 -0700] "POST /login_up.php3 HTTP/1.1" 200 5096 "-" "-"
[28/Apr/2012:21:58:43 -0700] "POST /login_up.php3 HTTP/1.1" 200 5096 "-" "-"
[28/Apr/2012:21:58:46 -0700] "POST /login_up.php3 HTTP/1.1" 200 5096 "-" "-"
[28/Apr/2012:21:58:48 -0700] "POST /login_up.php3 HTTP/1.1" 200 5096 "-" "-"
[28/Apr/2012:21:58:50 -0700] "POST /login_up.php3 HTTP/1.1" 200 5096 "-" "-"
[28/Apr/2012:21:58:53 -0700] "POST /login_up.php3 HTTP/1.1" 200 5096 "-" "-"
[28/Apr/2012:21:58:55 -0700] "POST /login_up.php3 HTTP/1.1" 200 5096 "-" "-"
[28/Apr/2012:21:58:58 -0700] "POST /login_up.php3 HTTP/1.1" 200 5096 "-" "-"
[28/Apr/2012:21:59:00 -0700] "POST /login_up.php3 HTTP/1.1" 200 5096 "-" "-"

These go on and on every few seconds.