Dispatcher Yellow SMDAgent Disconnected Solman

Dear Experts,

My SOLUTION MANAGER system was working fine but after a restart DISPATCHER remaining Yellow and SMDAgent is in DISCONNECTED state:

1. Entries in HOST file are right 

2. Network and Database working fine.

3. I don't have the parameter PHYS_MEMSIZE in my instance profile

4. J2ee_admin, SMDAgent UNLOCKED

What might be the problem guys.

Regards,

Domnic.