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I have two laptops with Ubuntu 10.04 installed. One of them had a problem; I was not sure if it was a hardware or software problem. Sometimes it would suddenly start working extremely slow (it needed a few minutes to open an application, such as a terminal window) and afterward the screen would become grey and inactive. After some time (5-10 minutes) it would start to work normally again.

I've installed Ubuntu 11.04 on an external drive. In the beginning it was working fine, but after some time (quite short) the same problem began to appear when the computer was running the system installed on the external drive. So I thought it was a hardware problem.

Yesterday I had to switch off the computer using the power button, since the problem persisted for at least half an hour. Since that time the system on the external drive has been completely broken; when I'm trying to boot the other computer with the system on the external drive, even GRUB doesn't show up (even after waiting about 20 minutes). When I boot the computer with the internal system, it can see the external drive partitions.

I was thinking that maybe that problem was connected with a virus; I've scanned the computer where the problem appeared with clamav, and found nothing.

Thanks for any tips.

P.S. The computer in question is Acer AS 3810T. CPU: Intel Core (tm)2 Solo processor SU3500(1.4GHz). RAM: 3GB DDR. Video card: Intel Graphics Media Accelerator X4500M HD

The external drive is ADATA HDD NH92.

Here are the screenshots showing the use of processor (on the panel) and System Monitor window (I'm not sure, but I think that there is something strange here, on the first screenshot the indicator of the use of processor is all blue and System Monitor doesn't show bigger use of processor): fist screenshot enter image description here

The slowing down doesn't happend when I'm doing something which demands more of processor of memory use. Just from time to time.

Processor speed is set on "ondemand" and it's varying from 800 MHz to 1.4 Ghz.

UPDATE:

It seems that it is the memory which is exessively used in the broken computer. The other one (Acer Aspire 2920Z; CPU Intel Premium Dual CPU t2370, 1.73GHz; RAM 2.0 GB), while exactly the same applications (at least the software that I run, I don't know about background processes) are in use, uses much less memory - the first one 95%, the other 60%. Applications used at the moment: two web browsers (Firefox and Chrome) and music player.

2nd UPDATE:

I have now on the top panel sytem monitor's indicators of use of CPU, RAM, system load (?) and swap. In the moment the system freezes first 3 of them are full (show 100%). Swap stays with the margin use, just few %. When it freezes I'm not able to check which process is taking most of CPU and memory, since no window works and either the muse coursor is blocked, or it mooves around the screed but doesn't make any effect. In the moment it freezed I had only the web browser open, but I was not using my computer at all, I just saw the screen loosing colours.

3rd UPDATE

Since I've removed antivirus (clamav), the system is no longer freezing, but still it happens (without any visible reason) to slow down. I don't know if the antivirus was the reason (one of the reasons), since I've removed it I was not using my computer a lot.

I've done memory test by memtest, no errors.

Quite often in the top of the list of processes using the most CPU is flushplugin-installer. Should't I use Firefox? I thought it's not an application demending a very fast processor...

Thanks

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@Scott The computer in question is Acer AS 3810T. The external drive is ADATA HDD NH92 –  maria Dec 17 '11 at 14:47
    
The model numbers of the laptop and external HDD are only part of the picture. Please give additional info, such as RAM details, video card details, and any other hardware info that has any small possibility of being relevant. Also, try booting up the computer and running System Monitor with the processes tab selected and see if your CPU is pegged when the slowdown happens (and which program is responsible). Also, check whether the hard drive light is going like crazy, which could be a sign of excessive swapping. –  Scott Severance Dec 17 '11 at 16:27
    
@ScottSeverance Thanks a lot. I've added the information you were asking, if there is something else which might be relevant, please, ask, I have no idea of what the problem might be. –  maria Dec 17 '11 at 17:20
    
The pegged processor could be a clue. In System Monitor, make sure that it's set to show processes from all users. I suspect that there's another process (perhaps root-owned) that's eating CPU. –  Scott Severance Dec 17 '11 at 17:30
    
@ScottSeverance I really don't understand it... I've opended also htop (since I don't know how to include root's processes in System Monitor), it shows something completly different... In System Monitr there is the biggest use of processor by the System Monitor itself (it might go even to 80-90 % of CPU), in htop window the biggest use of CPU by one process is around 3%... –  maria Dec 17 '11 at 17:45
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1 Answer 1

IO WAIT

Take a look at the "wait" (wa) when you do a top in a terminal, it will show you if your system is waiting after IO to process further instructions.

Tasks: 216 total,   2 running, 213 sleeping,   0 stopped,   1 zombie
Cpu(s): 13.8%us, 15.9%sy,  0.0%ni, 69.3%id,  1.0%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:   2020492k total,  1717168k used,   303324k free,    41664k buffers
Swap:  4796412k total,   374820k used,  4421592k free,   483220k cached

MEMORY

Check for defect/faulty memory by using the memtest86 option when you boot to grub. A lot of good tests are also mentioned here https://help.ubuntu.com/community/FaultyHardware

LIVECD

Check with the Ubuntu LiveCD if you still have the same problems. You may want to try UBCD also to do some hardware tests.

share|improve this answer
    
I don't know what do you mean by "wait" in top. When I run top, it starts immediately. I've done the memory test, no errors. –  maria Dec 26 '11 at 17:45
    
Ok, I've found "wa"; when I run 'top' it was changing from 1.7 to 0. I can't check it when the system slows down, since I can't do almost nothing. Even typing goes very slow... And still my main problem is broken system on external drive - why could it happen? Thanks –  maria Dec 26 '11 at 18:03
    
When it slows down, do the WA goes up ? –  jflaflamme Dec 27 '11 at 16:05
    
I don't know, since when it slows down, it takes to much time to open terminal etc, so usually it becames normal before I can run top. So I can't check it. –  maria Dec 27 '11 at 17:42
    
Then, i'm referring you to my first answer, about Memory tests and UBCD to check your hardware, hope it helps and answer your question –  jflaflamme Dec 27 '11 at 21:42
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