HEAD request on edubuntu-8.10-rc-addon-amd64.iso took longer than 30 seconds

[SWITCHmirror Admins]

Do other mirror admins also see this error in their prober logs for 
cdimages?

HEAD request on edubuntu-8.10-rc-addon-amd64.iso took longer than 30 seconds
Failed

Below is the complete prober file from an hour ago. The one from two 
hours ago looks identical, but the one three hours ago was flawless with 
no error reported!

We have no clue why that happens. It is not the first time, already 
earlier this week we experience it for about a day.
Always the same two files get reported with that time out, even they exist.

Due to these errors reported, our mirror got dropped from the list of 
mirrors :-(

Any hint is welcome.

Thomas

probe-logfile.txt
-----------------
http://mirror.switch.ch/ftp/mirror/ubuntu-cdimage///edubuntu/intrepid/edubuntu-8.10-rc-addon-amd64.iso: 
HEAD request on 
http://mirror.switch.ch/ftp/mirror/ubuntu-cdimage///edubuntu/intrepid/edubuntu-8.10-rc-addon-amd64.iso 
took longer than 30 seconds
Failed 
http://mirror.switch.ch/ftp/mirror/ubuntu-cdimage///edubuntu/intrepid/edubuntu-8.10-rc-addon-i386.iso: 
HEAD request on 
http://mirror.switch.ch/ftp/mirror/ubuntu-cdimage///edubuntu/intrepid/edubuntu-8.10-rc-addon-i386.iso 
took longer than 30 seconds
Found all ISO images for series The Intrepid Ibex and flavour kubuntu.
Found all ISO images for series The Intrepid Ibex and flavour ubuntu.

-- 
SWITCH
Serving Swiss Universities
--------------------------
Thomas Lenggenhager
P.O. Box, 8021 Zurich, Switzerland
http://mirror.switch.ch