I'm on a brand new 10.6.4, just installed last week from 10.6 to 10.6.3, then updated (not combo) into 10.6.4. On a macbook C2D.

So far no issue to signal, save today, I had a mix up in the mailboxes of Mail. Some were duplicated inside another one, and I add to manually move the files in the finder, rebuild boxes, re move again then suppress the offending folders. Now everything is fine.

Note it may be a glitch due partly to an issue in the rebuild of the databases Mail does when started first in 10.6.4, but it's good to know it's not a disaster.

In fact, a few of the rules I have to dispatch emails between folders have lost their destination. That's all.

Fortunately, it's only a few of them.

Note, for unknown reason, some users have troubles with Logic. It can be just a problem of the OS or software installed being corrupted in some way.

On my side, Mail has stopped with its strange ideas, but Safari quits unexpectedly. But the cause for Safari instability is in plug-ins and extensions, it'll be cleared once beta and new software will be corrected.

I'm trying right now:
extensions
- faceblock
- adblock
- invisiblehand
- reload button

plug-in
- glims
- clicktoflash

As I can't trace the origin of the unstablity, I'm trying them in turns…

For now adblock is guilty, so I will have to wait for the developer to smooth it.

installed back safari cookies, it works.