When I configured Solaris guest host on virtualbox I overlooked the kind of network adapter.It was set to be an pcnet adapter. I tried to forward the port 80 to host's 8080 port and gave proper VBoxManage commands on Win7 host. And tried to start VM.But it failed and gave the error I wrote on the subject of this post. I realised later that on solaris guest host there was an AMD adapter and now trying to port forwarding with a e1000 adapter lead to this error. To resolve this I manually deleted the corresponding lines at the XML config file under my home dir. Gave the correct adapter and forwarded its ports. And now it works.
Errare humanum est sed perseverare diabolicum.