Testei desligar o computador no estabilizador e tudo, e depois bootar direto o Live-CD, não deu do mesmo jeito. =/
Peguei o dmesg, aqui vai um pedaço dele:
[ 65.629666] eth0: Media Link On 100mbps full-duplex
[ 69.444331] lp0: using parport0 (interrupt-driven).
[ 73.436010] eth0: no IPv6 routers present
[ 73.498644] [drm] nouveau 0000:01:00.0: Allocating FIFO number 1
[ 73.502408] [drm] nouveau 0000:01:00.0: nouveau_channel_alloc: initialised FIFO 1
[ 86.805037] ------------[ cut here ]------------
[ 86.805057] WARNING: at /build/buildd/linux-2.6.32/net/sched/sch_generic.c:261 dev_watchdog+0x1fe/0x210()
[ 86.805063] Hardware name: System Name
[ 86.805067] NETDEV WATCHDOG: eth0 (sis900): transmit queue 0 timed out
[ 86.805073] Modules linked in: binfmt_misc lp dm_crypt snd_intel8x0 snd_ac97_codec ac97_bus snd_pcm_oss snd_mixer_oss snd_pcm snd_seq_dummy snd_seq_oss snd_seq_midi snd_rawmidi snd_seq_midi_event snd_seq ppdev bttv v4l2_common parport_pc ns558 snd_timer videodev v4l1_compat snd_seq_device gameport ir_common parport snd videobuf_dma_sg videobuf_core btcx_risc psmouse soundcore shpchp tveeprom i2c_sis96x snd_page_alloc serio_raw squashfs aufs nls_cp437 isofs dm_raid45 xor fbcon tileblit font bitblit softcursor vga16fb vgastate nouveau ttm drm_kms_helper drm sis_agp i2c_algo_bit agpgart sis900 mii
[ 86.805188] Pid: 2140, comm: bash Tainted: G M 2.6.32-21-generic #32-Ubuntu
[ 86.805193] Call Trace:
[ 86.805208] [<c014c3d2>] warn_slowpath_common+0x72/0xa0
[ 86.805218] [<c04d824e>] ? dev_watchdog+0x1fe/0x210
[ 86.805227] [<c04d824e>] ? dev_watchdog+0x1fe/0x210
[ 86.805237] [<c014c44b>] warn_slowpath_fmt+0x2b/0x30
[ 86.805245] [<c04d824e>] dev_watchdog+0x1fe/0x210
[ 86.805254] [<c0163980>] ? insert_work+0x60/0xb0
[ 86.805265] [<c012a438>] ? default_spin_lock_flags+0x8/0x10
[ 86.805274] [<c058b5af>] ? _spin_lock_irqsave+0x2f/0x50
[ 86.805282] [<c0163c46>] ? __queue_work+0x36/0x50
[ 86.805290] [<c015b63e>] run_timer_softirq+0x13e/0x2c0
[ 86.805300] [<c0176814>] ? tick_dev_program_event+0x74/0xd0
[ 86.805309] [<c04d8050>] ? dev_watchdog+0x0/0x210
[ 86.805317] [<c0153068>] __do_softirq+0x98/0x1b0
[ 86.805324] [<c02094d7>] ? __fput+0x177/0x1f0
[ 86.805332] [<c01531c5>] do_softirq+0x45/0x50
[ 86.805340] [<c0153315>] irq_exit+0x65/0x70
[ 86.805348] [<c058faec>] smp_apic_timer_interrupt+0x5c/0x8b
[ 86.805356] [<c0103df1>] apic_timer_interrupt+0x31/0x40
[ 86.805361] ---[ end trace 731486efb8fd2555 ]---
[ 86.805368] eth0: Transmit timeout, status 00000004 00000249
[ 94.804018] eth0: Transmit timeout, status 00000004 00000249
[ 102.805018] eth0: Transmit timeout, status 00000004 00000249
[ 110.804019] eth0: Transmit timeout, status 00000004 00000249
[ 118.805016] eth0: Transmit timeout, status 00000004 00000249
[ 126.805033] eth0: Transmit timeout, status 00000004 00000249
[ 134.122777] [drm] nouveau 0000:01:00.0: nouveau_channel_free: freeing fifo 1
[ 134.805064] eth0: Transmit timeout, status 00000004 00000249
[ 138.124439] [drm] nouveau 0000:01:00.0: Allocating FIFO number 1
[ 138.125960] [drm] nouveau 0000:01:00.0: nouveau_channel_alloc: initialised FIFO 1
[ 142.805032] eth0: Transmit timeout, status 00000004 00000241
[ 150.804021] eth0: Transmit timeout, status 00000000 00000251
[ 158.805022] eth0: Transmit timeout, status 00000000 00000240
[ 166.804015] eth0: Transmit timeout, status 00000000 00000240
[ 174.804020] eth0: Transmit timeout, status 00000000 00000260
[ 182.805017] eth0: Transmit timeout, status 00000000 00000260
[ 190.805012] eth0: Transmit timeout, status 00000000 00000260
[ 198.804016] eth0: Transmit timeout, status 00000000 00000260
[ 206.805017] eth0: Transmit timeout, status 00000000 00000260
[ 214.805015] eth0: Transmit timeout, status 00000000 00000260
[ 222.805016] eth0: Transmit timeout, status 00000000 00000260
[ 230.804017] eth0: Transmit timeout, status 00000000 00000260
[ 238.804018] eth0: Transmit timeout, status 00000000 00000260
[ 246.805032] eth0: Transmit timeout, status 00000000 00000260
[ 254.805023] eth0: Transmit timeout, status 00000000 00000260
[ 262.804019] eth0: Transmit timeout, status 00000000 00000260
[ 270.804018] eth0: Transmit timeout, status 00000000 00000260
[ 278.804025] eth0: Transmit timeout, status 00000000 00000260
[ 286.804017] eth0: Transmit timeout, status 00000000 00000260
[ 294.804014] eth0: Transmit timeout, status 00000000 00000260
[ 299.988011] Machine check events logged
[ 302.804015] eth0: Transmit timeout, status 00000000 00000260
[ 306.988015] eth0: Transmit timeout, status 00000000 00000260
[ 314.988015] eth0: Transmit timeout, status 00000000 00000260
[ 322.988018] eth0: Transmit timeout, status 00000000 00000260
[ 330.988023] eth0: Transmit timeout, status 00000000 00000260
[ 338.988016] eth0: Transmit timeout, status 00000000 00000260
[ 346.989014] eth0: Transmit timeout, status 00000000 00000260
[ 354.989013] eth0: Transmit timeout, status 00000000 00000260
[ 362.989013] eth0: Transmit timeout, status 00000000 00000260
[ 370.989017] eth0: Transmit timeout, status 00000000 00000260
[ 378.989016] eth0: Transmit timeout, status 00000000 00000260
[ 386.988026] eth0: Transmit timeout, status 00000000 00000240
[ 393.190152] kjournald starting. Commit interval 5 seconds
[ 393.190319] EXT3 FS on sda1, internal journal
[ 393.190326] EXT3-fs: mounted filesystem with ordered data mode.
[ 394.989021] eth0: Transmit timeout, status 00000000 00000240
[ 402.988046] eth0: Transmit timeout, status 00000000 00000240
[ 410.989034] eth0: Transmit timeout, status 00000000 00000260
[ 418.988019] eth0: Transmit timeout, status 00000000 00000240
[ 426.988019] eth0: Transmit timeout, status 00000000 00000260
[ 434.989030] eth0: Transmit timeout, status 00000000 00000260
[ 442.988019] eth0: Transmit timeout, status 00000000 00000240
[ 450.989022] eth0: Transmit timeout, status 00000000 00000260
[ 458.988017] eth0: Transmit timeout, status 00000000 00000260
[ 466.989017] eth0: Transmit timeout, status 00000000 00000260
[ 474.989022] eth0: Transmit timeout, status 00000000 00000260
[ 482.989017] eth0: Transmit timeout, status 00000000 00000260
[ 490.988018] eth0: Transmit timeout, status 00000000 00000260
[ 498.988018] eth0: Transmit timeout, status 00000000 00000240
[ 506.988020] eth0: Transmit timeout, status 00000000 00000240
[ 514.988024] eth0: Transmit timeout, status 00000000 00000240
[ 522.989019] eth0: Transmit timeout, status 00000000 00000240
[ 530.989019] eth0: Transmit timeout, status 00000000 00000240
[ 538.988022] eth0: Transmit timeout, status 00000000 00000240
[ 546.988021] eth0: Transmit timeout, status 00000000 00000240
[ 554.988019] eth0: Transmit timeout, status 00000000 00000260
[ 562.989012] eth0: Transmit timeout, status 00000000 00000240
Obrigado pela atenção!
EDIT:
Bom, pesquisei sobre essa mensagem do dmesg, e encontrei que é um conflito com ACPI, dei o boot no Live-CD do Kubuntu com opção de acpi=off e funcionou perfeitamente!
Agora quero saber como faz pra dar boot com acpi=off no Ubuntu, porque não achei essa opção nesse tipo novo de boot que tá no 10.04, só no kubuntu que é do jeito antigo que achei o
E também quando eu instalar, como farei para ele ligar sempre com acpi=off, para não me causar problemas!
Obrigado a todos!