We managed to get an answer for this issue, so I publish it in case anyone got the same issue.
The client agent was under impression he had some task to do and was constantly requesting core server for the task while no task did exist on the server. To solve this :
1-Launch CMD.EXE as administrator on the client machine
2-Issue the commands:
CD "C:\Program Files (x86)\LANDesk\Shared Files\cbaroot\"
3-Remove the line "landesk.provisioning=C:\ldprovisioning\LaunchLdprovisionAsUser.exe C:\ldprovisioning\ldProvision.exe -c PEBLNDSK01 -t C:\ldprovisioning -w 15 -r 20" from the file
4-save the file
5-open the file again with NOTEPAD to be sure that the modification has been saved.
6-Reboot the machine
(alternatively stop all the Intel and Landesk services on the device and start them again)