All right, that was it. For my case, the problem was the APIC on the kernel on my laptop. If I boot with "noapic" added to the kernel boot line, i can use fglrx with DRI acceleration and no usb freezing. I'm running it since i posted the comment and working great.
-- [FGLRX] kernel drivers kills USB subsystem https://launchpad.net/bugs/41272 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
