OT: Computer Problem

Sounds suspiciously like a power supply problem. Check voltages and ripple/noise on all PSU outputs. *Especially* ripple/noise! Should be 50mV P-P on +5V, -5V (if present) and +3.3V outputs, up to 120mV P-P on the +12V and -12V outputs. Voltage tolerances are +/- 5% on all outputs except the negative supplies, which is +/-10%.

Dave M

PSU problems don't match up with...

"The system seems to work ok while off-line." ...Jim Thompson

Depending on your resources/configuration, try swapping around/re seating your memory sticks... Or take one pair out etc.

XP has NO protection against current virus/malware attacks. I recommend you never hook up an XP machine online, or if hooked up never use a browser. Far too many search engine results are compromised to trust the vintage of browser that will only work on XP.

A patch you need to install if you are running XP:

John :-#(#

Only browsing? XP tended to have memory leaks, which you could get from opening and closing a lot of jpegs or something. Eventually you'd run out of RAM and have to reboot.

Win7 is a lot more stable than XP.

I suggest you try these first:

Clear accumulated junk with Ccleaner

and scan your HDD for defects with HDTune

The free versions work well enough for most people.

Yep - I agree. I think your software is screwed up.

When you ask an auto mechanic for help, what is the first thing he asks? Hint: Maker and model number.

Windoze XP suggests that it might be up to 15 years old. Old computers tend to have bulging capacitor problems, which is probably the most common component failure. Also on the old computer list of headaches are AMD processors, which overheat quite easily.

Offhand, I would guess(tm) that you either have:

1. Bulging electrolytic caps on the motherboard
2. Bulging electrolytic caps in the power supply
3. Bulging electrolytic caps on the video card
4. Some program that's running in the background going nuts.

The first three can be checked physical inspection, substitution, or ESR tester. For software, check: Control Panel -> Admin Tools -> Event Viewer and see if there's any complaints just before it crashes or reboots.

Also, download and make a bootable floppy or CD a memory tester: Run it for a while and later overnight. If it finds anything wrong, you have a hardware problem somewhere. Bulging caps tend to work better when the machine is warm, so cool down the machine before running the test.

There's also a memory test program on the boot menu of most Linux LiveCD disks. Since we're not sure if it's hardware or software, you might try running the Linux LiveCD for a while and see if the problems are still present. If so, then it's certainly hardware. If not, then there's something wrong with your Windoze XP installation.

My experiance....

Faulty Power switch in case ( like a logitech mouse button failure). Bad CD-ROM drive. On a laptop caused XP to hang. Bad Memory stick. Swapped out/around until the bad one was found. Video Card. Always have problems with the performance stuff, keep a cheap card around for sanity checks.

Cheers

How do bulging capacitors effect the operation only while connected to the internet? Machine works fine while off-line.

The browsers tend to use a lot of resources, ram and esp. gfx which tends to aggravate(that means worsens) power supply troubles.

As you say, it shouldn't. When customers offer me a list of symptoms and background, there are almost always inconsistencies which make no sense. In this case, it could be real, such as you only use the ethernet or wireless card while online. There could also be multiple causes, some of which interact, causing the crash or hang. So, for a first guess(tm) as to the cause, I take the most obvious and common symptoms, and relate them to the most obvious and common culprits. I do what's easiest first, and then move on to more exotic and complexicated possible causes.

In this case, you have what I would guess(tm) to be an old computer, with a high probability of running old software and drivers, and is likely to have bulging caps. Once you have inspected the insides, blown the dust out of the machine, reseated all the connectors, inspected the electrolytic caps, perhaps tested the caps with an ESR tester, and tried some basic diagnostics (MEMTEST, Linux LiveCD, measure power supply voltages), we can then discuss the relative merits of your initial speculations. In other words, I really don't care if your suspicions are right or wrong. I only care about fixing the machine. Please note that fixing the machine is your problem, not mine.

Is there some reason that you seem to be unwilling to disclose the maker and model of the machine? I'm also interested in why you seem to favor diagnosis by logic rather than follow my rather simple and easy diagnostic suggestions?

the

day.

to

It appears the problem is more advanced than I thought. Since my last post I have replaced the power supply and the disk with no help. The system still locks up and the mouse frezzes at random times. I tried safe mode with same result. I finally got it to bootup to the desktop screen and the mouse was working for about an hour and then froze. I tried another mouse with same result so I don't think the problem is the mouse. So it must be the main board with some intermittent part or maybe the BIOS. This machine has been in operation for a couple years with no virus protection. So I'm thinking some virus has updated the BIOS to cause trouble. The problem slowly developed with only an ocassional lock-up every few days and then rogressively got worse so the mouse no longer works today for more than a couple minutes. However, the situation seems to improve as the system warms up so it may be a thermal problem. I've looked at the main board and don't see any electrolytic capacitors that are bulging.

Anyway, I've been wanting a laptop for a couple years to replace the ugly desktop, so this might be a good time to just throw the thing in the trash and replace it with a laptop with WIFI. We have public WIFI where I live so I wouldn't need a private connection. I don't do anything on the web that requires security, so it doesn't matter what anybody steals from my computer since it's all worthless information.

that fits the symptoms of a bad electrolytic filter cap EXACTLY.

The ESR improves as the cap warms up to the point where it works OK.

Seen it several times. Look for a bad cap on one of the power supplies that are on the mother board.

The standard thing is to test by running memtest off a boot from CD linux distribution. If it still fails the same sort of ways then you have a hardware problem. Bulging or leaning capacitors near the memory chips would be my second guess if reseating the memory doesn't cure it.

Swapping bad capacitors on an otherwise good motherboard is possible iff a little nerve racking - backup everything you are fond of first!

Needs a steady hand and a fairly powerful soldering iron but at least the damn things only have two pins. They are often the weakest link.