Which version did you install because my 10.04 also suddenly goes to the
black flashing screen when I move the mouse or hit a suddenly different
or wrong key. It does not do it every time, but its annoying when it
does. I would be interested in the answers to this one. In previous
version it never ever happened.

Rather than switching off with the button, try
holding Down "alt +sysreq" then, while holding
those down, slowly type "reisub". This is a safer way to
reboot your machine than holding down the power
button. You can look that command up in wikipedia
or on this list for more info on how it works. Then if
it doesn't work, at that point you go to the button push.
The reisub method provides a way (usually) to reboot a
Locked machine w/o damaging any system files
on the drive.

As far as your problem goes, did you do the
md5checksum on the disk before installation?
(that is assuming it was a disk install and not
Just an in-place instal). If you don't have too
much time invested into the new system yet
It could be worth it to try reinstalation in
Case something went wrong there. But
it would probably be smarter to wait a bit
and see what some more of the people
around here that are a lot more in the
know than me have to say.

it may be the way to shut down but in my case it would not work
because although you can use the keyboard I cant see the desktop.

i'm not ble to use the key board or mouse when it freezes up
my only option is to hit the power button.
i'm using
10.04
this is my third attempt at sending this as i've had to switch off and reload 3
times in the last ten mins.

it's not just while using the firefox browser it's while putting a usb dongle on
as well

there has been a lot of "freezing" situations so just be clear:
You can not move the mouse or use buttons on the keyboard (like Alt + F)
and even after waiting say 10 minutes - the computer is still frozen.

If you can move the mouse around then you have a slightly different issue.

As for total freezing - if you are on 10.04 you can either move on to
10.10 or back to 9.10.

In my case the screen suddenly turns black with flashing lighting from
the top of the screen, I cannot see the desktop or use mouse or keyboard
and leaving it for a period makes not difference its still frozen.

It leave no alternative but a power shut down.

This problem if filling the Ubuntu forums. People have reported unstable
9.04 but mainly 10.04.

I guess I need to load 10.04 on another computer and see if I still have
issues since swapping out so many components. And right now, Im still on
11.04.

Is that 11.04 alpha ?.......................

does the sound go as well as the screen? If you haven't noticed,
could you try playing some music and see if you can still hear it when
the screen goes blank and let us know?

Also, I can't remember if you've mentioned whether or not this is a
laptop. It may not be relevant but...

Also, could you tell us what video card and driver you have (lspci -vv
[that's two 'vee's not a 'double-you', just in case it's as unclear on
your monitor as it is on mine :-)] or sudo lshw in a terminal)?

No I have not tried playing music, if it does, it may help calm a
frustrated user. I have put up on the list my computer spec many times
before but will say again this is an older desktop computer.

This is my read out, it not a power base but then I do not use it for
games or grapic work

ian@ian-desktop:~$ lspci -vv
00:00.0 Host bridge: Intel Corporation 82845G/GL[Brookdale-G]/GE/PE DRAM
Controller/Host-Hub Interface (rev 01)
Subsystem: Dell Device 0160
Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr-
Stepping- SERR+ FastB2B- DisINTx-
Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort-
SERR-

Kernel driver in use: agpgart-intel
Kernel modules: intel-agp

00:02.0 VGA compatible controller: Intel Corporation
82845G/GL[Brookdale-G]/GE Chipset Integrated Graphics Device (rev 01)
Subsystem: Dell Device 0160
Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr-
Stepping- SERR- FastB2B- DisINTx-
Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort-
SERR-

Kernel modules: i915

00:1d.0 USB Controller: Intel Corporation 82801DB/DBL/DBM
(ICH4/ICH4-L/ICH4-M) USB UHCI Controller #1 (rev 01)
Subsystem: Dell Device 0160
Control: I/O+ Mem- BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr-
Stepping- SERR- FastB2B- DisINTx-
Status: Cap- 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort-
SERR-