Today while installing VMware vCenter Inventory Service, I noticed that the installer would "hang" after I clicked the Next button on the page where you enter in the vCenter SSO service's URL (vCenter Signle Sign On Information page). First, I opened up the vminst.log file and noticed things were stopping on the following line:
VMware VirtualCenter-build-947673: 03/06/13 09:12:35 Attempting to launch ["C:\Users\ADMINI~1\AppData\Local\Temp\3\{946581B4-C0B9-4A86-9207-E64448CBA66B}\openssl.exe" x509 -noout -checkend 0 -in "C:\ProgramData\VMware\Infrastructure\Inventory Service\ssl\rui.crt" ]

Solution:
The reason I was receiving this issue was due to the way I had prestaged my SSL certificates. For whatever reason, I had missed setting up my VMware SSL directory (C:\ProgramData\VMware\SSL) and thus did not have the ca_certificates.crt and the whatever.0 hash file. Once I had placed those files inside of the C:\ProgramData\VMware\SSL directory, the installer was able to continue on.