SHORT SUMMARY: When several signed applets are simultaneously loaded
  from the same web page, some of them may not get full permissions.
INDICATORS: Different kinds of AccessControlException's that are not
  supposed to be thrown for signed applets (for example, on reading
  "user.home" property, or on accessing a local file system).
TRIGGERS: The problem happens sporadically and have symptoms of
  a race condition with low-to-medium failure rate.
KNOWN WORKAROUND: Though there is no direct relation between this change
  and the problem's root cause, disabling the Java Deployment Cache helps
  to avoid the problem.
PRESENT SINCE: Introduction of plugin2, at least.
HOW TO VERIFY: There is no stand-alone test case for this issue.
  The customer verifies the provided binaries in their environment
  and informs us about the verification results.
REGRESSION: No.