Let me guess, you are using a proxy or Windows XP? VMware will tell you its an OS issue and to refer you to http://support.microsoft.com/kb/948963.
My fix was restoring the original Tomcat server config, comparing what changed, and putting it back. I take no responsibility if this breaks something else, but it fixed my problem (which is exactly the same error you seem to be having -- missing hardware status tab / 2 errors in the plug-in).
Backup and edit this file: C:\Program Files\VMware\Infrastructure\tomcat\conf\server.xml
Locate this line:
<Connector SSLEnabled="true" acceptCount="100" ciphers="TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA, TLS_ECDH_RSA_WITH_AES_256_CBC_SHA, TLS_DHE_RSA_WITH_AES_256_CBC_SHA, TLS_DHE_DSS_WITH_AES_256_CBC_SHA, TLS_DH_RSA_WITH_AES_256_CBC_SHA, TLS_DH_DSS_WITH_AES_256_CBC_SHA, TLS_RSA_WITH_AES_256_CBC_SHA, TLS_DHE_RSA_WITH_AES_128_CBC_SHA,TLS_RSA_WITH_AES_128_CBC_SHA, TLS_DHE_DSS_WITH_AES_128_CBC_SHA, TLS_DH_RSA_WITH_AES_128_CBC_SHA, TLS_DH_DSS_WITH_AES_128_CBC_SHA" connectionTimeout="20000" executor="tomcatThreadPool" keystoreFile="${bio-vmssl.keyFile.name}" keystorePass="${bio-vmssl.SSL.password}" keystoreType="PKCS12" maxKeepAliveRequests="15" port="${bio-vmssl.https.port}" protocol="HTTP/1.1" redirectPort="${bio-vmssl.https.port}" scheme="https" secure="true"></Connector>
Replace it with this:
<Connector SSLEnabled="true" acceptCount="100" ciphers="SSL_RSA_WITH_RC4_128_MD5, SSL_RSA_WITH_RC4_128_SHA, TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA, TLS_ECDH_RSA_WITH_AES_256_CBC_SHA, TLS_DHE_RSA_WITH_AES_256_CBC_SHA, TLS_DHE_DSS_WITH_AES_256_CBC_SHA, TLS_DH_RSA_WITH_AES_256_CBC_SHA, TLS_DH_DSS_WITH_AES_256_CBC_SHA, TLS_RSA_WITH_AES_256_CBC_SHA, TLS_DHE_RSA_WITH_AES_128_CBC_SHA, TLS_RSA_WITH_AES_128_CBC_SHA, TLS_DHE_DSS_WITH_AES_128_CBC_SHA, TLS_DH_RSA_WITH_AES_128_CBC_SHA, TLS_DH_DSS_WITH_AES_128_CBC_SHA, SSL_RSA_WITH_3DES_EDE_CBC_SHA, SSL_DHE_RSA_WITH_3DES_EDE_CBC_SHA, SSL_DHE_DSS_WITH_3DES_EDE_CBC_SHA" connectionTimeout="20000" executor="tomcatThreadPool" keystoreFile="${bio-vmssl.keyFile.name}" keystorePass="${bio-vmssl.SSL.password}" keystoreType="PKCS12" maxKeepAliveRequests="15" port="${bio-vmssl.https.port}" protocol="HTTP/1.1" redirectPort="${bio-vmssl.https.port}" scheme="https" secure="true"></Connector>
Restart the WebManagement service to take effect.
I basically restored the missing ciphers (RC4/SSL/3DES) that were present in VCenter 5.0. It's probably less secure, but it fixes the issue. To the VM developers who though SSO was a brilliant idea and the QA testers who made 5.1 possible... I really really hate you.