Starting from jre 1.6u10, browser integration uses a so-called "next-generation plugin".
Some old applications are not compatible with it, and (on windows) it could be disabled in control panel, java, Advanced, Java Plug-in, remove the check from "Enable the next-generation Java Plug-in (requires browser restart)".
The problem is that sometimes this check is grayed out, and it is not uncheckable even if you have amdinistrative priviledges and run as administrator.
Any workaround to solve this?
UPDATE:
I've done some testing on some machines with different operating systems, browsers and java versions.
Initially I've supposed that the problem was w 7 or the fact that it was a 64 bit o.s., but there is a case (case 3) that denies this assumption.
So there is something "else" on a machine that determines this option to be grayed out.
Test O.S Browser JRE version State
1 W 7 64 (Home) IE 9 7u2 64 grayed out
2 W 7 64 (Bus) IE 8 6u27 64 grayed out
3 W 7 64 (Bus) IE 9 6u22 64 NOT grayed out