I can't pinpoint the exact revision since after 409, there was a bug that causes games to crash when transitioning to new areas. But since that bug got fixed, a new one popped up in Resident Evil 4 that wasn't in 4.0 409. When you enter the fly cave after beating the the two El Gigentes, the game freezes when you enter one of the smaller caves that has a button to activate the light to open a door.
You should pinpoint the exact revision that introduced the issue and report it on Dolphin's Google Code page. It's the best way to bring up a problem to the attention of the devs, thus making it more likely to be fixed. Believe it or not, but a number of devs don't like using the forum (and not just as it pertains to fixing Dolphin related issues) so be sure to let them know on the project's page.
4.0-411 caused regressions and was recently reverted, if I'm not mistaken.
I think he's saying that revision 4.0-434 corrected the main bug everyone was experiencing since 4.0-410, but that even after 4.0-434 there is still a new bug that wasn't in 4.0-409 affecting at least Resident Evil 4. I did have one crash transitioning areas in Twilight Princess since 4.0-434, but that's in over 4 hours of play so it may be unrelated.
I can't test those in between since they randomly freeze but all I can tell you is the game just freezes while the emulator is still running, no errors pop up or anything. I'm thinking this is a JIT issue since stepping on the wrong button in the castle does the same thing.