システムは動いているようだったんですが、画面はグチャグチャ。

どうもboot:オプションを指定すればよいらしいという感じです。
http://www.alpha.co.jp/biz/products/knoppix/faq/download_starting.shtml
まぁ時間ができたら試してみましょう。

ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver起動時にsleepを入れるとメッセージが変わってくるので内部電圧などが不安定なのかもしれないと感じてもいます。
ar71xx-ehci ar71xx-ehci: Atheros AR91xx built-in EHCI controller
ar71xx-ehci ar71xx-ehci: new USB bus registered, assigned bus number 1
ar71xx-ehci ar71xx-ehci: irq 3, io mem 0x1b000000
ar71xx-ehci ar71xx-ehci: USB 2.0 started, EHCI 1.00
usb usb1: configuration #1 chosen from 1 choice
hub 1-0:1.0: USB hub found
hub 1-0:1.0: 1 port detected
nf_conntrack version 0.5.0 (460 buckets, 1840 max)
CONFIG_NF_CT_ACCT is deprecated and will be removed soon. Please use
nf_conntrack.acct=1 kernel parameter, acct=1 nf_conntrack module option or
sysctl net.netfilter.nf_conntrack_acct=1 to enable it.
usb 1-1: new high speed USB device using ar71xx-ehci and address 2
usb 1-1: device descriptor read/64, error -71
ath_hal: module license 'Proprietary' taints kernel.
Disabling lock debugging due to kernel taint
ath_hal: 2009-05-08 (AR5210, AR5211, AR5212, AR5416, RF5111, RF5112, RF2413, RF5413, RF2133, RF2425, REGOPS_FUNC, XR)
usb 1-1: device descriptor read/64, error -71
usb 1-1: new high speed USB device using ar71xx-ehci and address 3
ath_pci: trunk
wlan: trunk
wlan: mac acl policy registered
ath_rate_minstrel: Minstrel automatic rate control algorithm 1.2 (trunk)
ath_rate_minstrel: look around rate set to 10%
ath_rate_minstrel: EWMA rolloff level set to 75%
ath_rate_minstrel: max segment size in the mrr set to 6000 us
ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver
Initializing USB Mass Storage driver...
usbcore: registered new interface driver usb-storage
USB Mass Storage support registered.
usb 1-1: device descriptor read/64, error -71
usb 1-1: device descriptor read/64, error -71
usb 1-1: new high speed USB device using ar71xx-ehci and address 4
usb 1-1: device descriptor read/8, error -71
usb 1-1: device descriptor read/8, error -71
usb 1-1: new high speed USB device using ar71xx-ehci and address 5
usb 1-1: device descriptor read/8, error -71
usb 1-1: device descriptor read/8, error -71
hub 1-0:1.0: unable to enumerate USB device on port 1