I just installed a keyless evaluation vCenter 4.0 and alternated the HTTPS port to 8448 and HTTP port as 8088 (vc4-ports-output.png). Then I add (licensed) ESXi 4 to my vCenter and it appears error while it is running 80% and shown the error message: "Cannot install the vCenter agent server. Unknown installer error" (vc4-esx4i-add-error-output.png). Should it the problem from alternated TCP/IP port number? Thanks!
Looks like there is some problem to install agent in ESXi host. Can you upload the log files? You can go to File->Export->Export Systems Logs from vSphere Client.
Yes. Need to do everything possible to make hypervisor got more physical
memory. I chose the easy way - reduced memory allocated to
one of my VM. Another way, I think it is also possible to make System Resource Reservation for memory in System Resource Allocation.