Can't play sound files with aplay or cat to /dev/dsp

I am having problems using soundes. Until a few moments ago
the following commands produced errors and no sound:

cat /usr/share/apps/kolf/sounds/blackhole.wav/ > /dev/dsp yielded:
/dev/dsp: Invalid argument

cat /usr/share/apps/kolf/sounds/blackhole.wav > /dev/audio yelded:
/dev/audio: Invalid argument

aplay /usr/share/apps/kolf/sounds/blackhole.wav yielded:
main:590: audio open error: No such file or directory

and yet mplayer was happily playing audio with tv video. For that program the video is set up for drive 0 but for spurious reasons the program has to be fiddled to use drive 1. The camera, BT787, and VIA 8235 cards are 0, 1, 2 respectively. I don't know if this is related.

Now for no apparent reason it has started working. This is not a connection problem. It had been working until I installed Timidity++ which errors out also.
This is a 4 day headache so would make me happy if someone has a solution.
BTW I have seen suggestions to remove PCM add PCM, fiddle with XMMS and other supposed solutions. In scanning ALSAhowto I could find nothing that could link the responses I am getting. Thanks.

What is your hardware? Be specific, including soundcard or motherboard model, etc. What is your kernel? What is you ALSA version? What does lsmod show? What does ls /sys/module show? Is there anything relevant looking in dmesg ?

Hardware: KT4V-L
Soundcard: none; sound via mobo
Kernel: 2.6.29.6-smp
ALSA version: 1.0.18a (came with Slackware 13.0)
Sound modules from /sys/module:
snd
snd_ac97_codec
snd_bt87x
snd_hwdep
snd_mixer_oss
snd_mpu401_uart
snd_page_alloc
snd_pcm
snd_pcm_oss
snd_rawmidi
snd_seq
snd_seq_device
snd_seq_dummy
snd_seq_midi_event
snd_seq_oss
snd_timer
snd_usb_audio
snd_usb_libsnd_via82xx

lsmod (edited):
Module Size Used by
xt_tcpudp 2620 61
xt_limit 1824 22
xt_state 1756 7
x_tables 13280 8 xt_tcpudp,xt_limit,xt_state,ipt_MASQUERADE,ipt_REJECT,ipt_LOG,iptable_nat,ip_tables
snd_seq_dummy 2464 0
snd_seq_oss 29792 0
snd_seq_midi_event 5980 1 snd_seq_oss
snd_seq 47984 5 snd_seq_dummy,snd_seq_oss,snd_seq_midi_event
snd_pcm_oss 37728 0
snd_mixer_oss 14300 1 snd_pcm_oss
fuse 54008 5
ppdev 7200 0
tuner_simple 14288 1
tuner_types 13884 1 tuner_simple
tuner 27620 0
tvaudio 26332 0
snd_usb_audio 80352 0
bttv 191828 0
ir_common 39872 1 bttv
snd_usb_lib 15228 1 snd_usb_audio
snd_via82xx 22772 0
snd_hwdep 6816 1 snd_usb_audio
snd_ac97_codec 100128 1 snd_via82xx
v4l2_common 14268 3 tuner,tvaudio,bttv
sn9c102 140292 0
gspca_sonixj 16476 0
gspca_main 21564 1 gspca_sonixj
ac97_bus 1372 1 snd_ac97_codec
videobuf_dma_sg 10784 1 bttv
psmouse 41676 0
videodev 38688 6 tuner,tvaudio,bttv,v4l2_common,sn9c102,gspca_main
snd_mpu401_uart 6524 1 snd_via82xx
snd_bt87x 11780 0
videobuf_core 15520 2 bttv,videobuf_dma_sg
serio_raw 5024 0
evdev 9152 7
i2c_viapro 7440 0
via_rhine 21700 0
snd_pcm 68128 5 snd_pcm_oss,snd_usb_audio,snd_via82xx,snd_ac97_codec,snd_bt87x
v4l1_compat 13184 1 videodev
btcx_risc 4196 1 bttv
rtc_cmos 10124 0
snd_rawmidi 19040 2 snd_usb_lib,snd_mpu401_uart
snd_seq_device 6088 4 snd_seq_dummy,snd_seq_oss,snd_seq,snd_rawmidi
via_agp 7900 1
mii 4380 1 via_rhine
parport_pc 24036 1
rtc_core 15992 1 rtc_cmos
thermal_sys 10756 2 thermal,processor
agpgart 29256 1 via_agp
snd_timer 19108 2 snd_seq,snd_pcm
shpchp 31888 0
snd 50820 14 snd_seq_oss,snd_seq,snd_pcm_oss,snd_mixer_oss,snd_usb_audio,snd_via82xx,snd_hwdep,snd_ac97_codec,snd_mpu401_uart,snd_bt87x,snd_pcm,snd_rawmidi,snd_seq_device,snd_timer
rtc_lib 2332 1 rtc_core
parport 30700 3 lp,ppdev,parport_pc
soundcore 5824 1 snd
snd_page_alloc 7972 3 snd_via82xx,snd_bt87x,snd_pcm
dmesg (sound related):
via82cxxx 0000:00:11.1: VIA vt8235 (rev 00) IDE UDMA133
via82cxxx 0000:00:11.1: IDE controller (0x1106:0x0571 rev 0x06)
pci 0000:00:11.1: can't derive routing for PCI INT A
via82cxxx 0000:00:11.1: not 100% native mode: will probe irqs later
ide0: BM-DMA at 0xfc00-0xfc07
ide1: BM-DMA at 0xfc08-0xfc0f
gspca: main v2.4.0 registered
sn9c102: V4L2 driver for SN9C1xx PC Camera Controllers v1:1.47pre49
sonixj: Sonix chip id: 11
gspca: probe ok
gspca: probing 0c45:60fc
sonixj: registered
VIA 82xx Audio 0000:00:11.5: PCI INT C -> Link[LNKC] -> GSI 5 (level, low) -> IRQ 5
VIA 82xx Audio 0000:00:11.5: setting latency timer to 64
Does that help?

snd_pcm_oss
...
snd_mixer_oss

Using the kernel's built-in OSS emulation for ALSA will let anything that uses OSS devices hog the raw sound device in the old-fashioned OSS way. You might want to disable that in the kernel and use ALSA's alsa-oss compatibility library instead.