I has been reported that FIM 3.1.2 has issues handling authentication request that take longer then 5 minutes to complete. If a end user takes longer than this time to provide its credential, the authentication attempt will fail.

On the SP side of things the following stacktrace would appear in FIM's log:

2008-06-20 16:30:04,943, (SSOHelper.java:607), cls-wlg-sa-d2, , , , Unable to process the Response message, com.rsa.fim.exception.ProfileException: The SAML Response issuer is not the same entity to whom the corresponding request was sent
                at com.rsa.fim.profile.util.ProfileHelper.checkResponseIssuer(ProfileHelper.java:1752)
                at com.rsa.fim.profile.sso.SSOProfileBean.processResponse(SSOProfileBean.java:1476)
                at com.rsa.fim.profile.sso.SSOProfile_5wyj3w_EOImpl.processResponse(SSOProfile_5wyj3w_EOImpl.java:46)
                at com.rsa.fim.servlet.sso.AssertionConsumerService.doGet(AssertionConsumerService.java:64)

The above mentioned timeout of 5 minutes was hardcoded within FIM and could not be changed.