Xorg Problems upgrading to 4.0

[kyuupichan]

I was running a current kernel from about 3 months ago reasonably happily, and decided to upgrade to current yesterday.

Unfortunately after upgrading I noticed X would freeze within a minute or two; I tried downgrading to 3.8 but that didn't work, failing during make installworld leaving the system unusable...

So I installed 4.0.1 fresh from the website today, and my usual packages.  Again X is freezing after a minute or two; however the kernel continues to run fine as I can log in via SSH.

I've attached my dmesg and Xorg.log.

Some things that might be causing it:

a) The new USB subsystem.  I have a USB mouse and a old PS2 keyboard/mouse combo; there is only a keyboard physically attached via the PS2 interface.  I'm using /dev/sysmouse as my mouse device for X; it works fine in the console.
b) I am pretty sure it's picking up KMS and DRI / graphics acceleration for the first time.  I have an AMD Radeon HD 6310 on-board GPU.  This GPU has only been moderately well supported historically (unsure if the issue was the kernel or X) e.g. once I go into X I cannot return to a text console - the screen goes blank but I can then return to X with Ctrl-Alt-F9.  This continues to be true with Dragonfly 4.0.

Any ideas / advice?  I'd like to not be stuck on 3.8 forever.

Neil.
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