If the old server is still available, you need to import the cert from it. I don't have the instructions handy, but they are here on this site and recently in the forums.
If not, try redeploying the agent to the machine and see if that fixes it.
there is no way to get old certificate,
reinstalling the client fix the problem
how do I reinstall cleints on all boxes without manully do it on each desktop?
If scheduling an agent deployment (full install, not an update to agent settings) does not fix the install, you may need to make a script that runs the agent uninstall first.
i've just ran full redeployment but it only worked for boxes I already manually reinstall the agent
while all other boxes giving me 1087 error "unable to connect .....
how do I check?
in properitys on the sheduled process owner domain admin user account
scope by user dmain admin account
On you core server do the following:
Start | Run type services.msc
find the LANDesk Scheduler Service (double-click on it)
click on the Log On tab
Enter a domain admin account
domain\user is the context needed.
logged in as local system account
that account wont work for deploying new agents. needs to be a domain admin.