Sorry I was kind of unsure which product you are using because you posted in the VMware Workstation forum and talked about "VMware Infrastructure".
Did you already check the Windows Firewall to see whether Windows did block traffic after detecting the connection to the new switch? You may try to delete the arp cache on the Windows 7 host to see if this makes a difference.
André
PS: Discussion moved from VMware Workstation to VMware Server 2 General Issues