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We've been experiencing this problem at the office for a while, on three different machines so far. CPUs are all Fujitsu Siemens with Windows XP installed, monitors are either Diunamai or Dell.

The problem can occur at different times on each machine: when you start the CPU, right after you've logged in on Windows or even while you're using the computer.

What happens is that, all of a sudden, the monitor stops receiving any signal from the CPU, which is still working, and just displays the "no signal" message.

In addition to this though, the CPU becomes impossible to turn off unless you unplug it, i.e. cut off its power. Pressing the reset button won't work anymore after the CPU's stopped sending signal to the monitor.

Now, one of our technicians replaced the VGA cable on one of those three machines and found out the computer is working again, but that can't really be the source of the problem, or that thing with the reset button wouldn't happen each time, right?

One computer showed this problem whenever I would log in on windows with my account and mine only, but not with others'; then the problem extended to other accounts on that machine; how can it be really solved just by changing a VGA cable?

Another of the machines affected used to stop sending the signal to the monitor every now and then while used, but it was still possible to work on it for some time. Back from vacation, I found out that pc wouldn't even turn on at all(a green light would blink for a while after pressing the power button on the CPU, then it'd go off with the whole machine); and today, after having obviously not being used for days, the CPU DOES turn on again, but isn't sending any signal to the monitor (again, pressing the rest button won't work).

I've run Malware Bytes on at least one of those three machines and haven't found anything (that's not our main antivirus, but it proved useful in the past to get rid of some rogue malware and trojans that mcAfee wasn't able to detect).

Any ideas?

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Dani AI

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Intermittent “no signal” while the PC still appears powered — and a front‑panel reset that stops working — points more to hardware than to pure malware or a simple bad cable. reported this across several Fujitsu Siemens Windows XP machines; ’s tip to open the case and check for loose parts is a sensible quick check, but the reset-button symptom requires deeper, methodical isolation.

Quick isolation checklist:

  • Swap monitor and VGA cable with known-good units to rule out cable/monitor (a cable swap fixed one machine briefly).
  • Observe system responsiveness: HDD/SSD activity LED, fan spin, and Caps Lock/Num Lock LED behavior. If keyboard LEDs toggle, the OS may still be running while video/driver fails.
  • Boot to Safe Mode or a Linux live USB. If video is stable there, the problem is likely a driver or user-profile startup item.
  • Check Windows Event Viewer (System/Application) for display-driver crashes or kernel power events once the machine can be booted.

Hardware-focused checks and how to interpret them:

  • Inspect PSU and motherboard for swollen or leaking electrolytic capacitors and burned components. Age-related capacitor/PSU failures commonly cause random signal loss and power irregularities.
  • Reseat the video card and RAM; try one memory stick at a time. Swap to integrated video (or a spare GPU) to isolate the GPU.
  • Test the front-panel reset switch: with power on and case open, momentarily short the two reset-header pins on the motherboard; if that forces a reset the case switch/wiring is bad. If shorting the header does nothing, the motherboard reset circuit or the PSU is probably at fault. Use extreme caution when working on a powered board — if unfamiliar, have a qualified technician do this.
  • If the PSU shows flaky behaviour (LED blink then off, intermittent failure to start), substitute a known-good PSU or use a PSU tester/multimeter to check 5V/12V rails.

A final note: because one machine initially failed only under a single user account, also consider profile-specific startup software or corrupted display settings — disable startup items via msconfig or create a fresh user profile for comparison. If any step involves mains probing or live‑board shorts and there is uncertainty, arrange hands‑on service: mains and ESD hazards are real.

Member Avatar for jingda

Take out the computer case and check whether there are any loose parts or screw inside. Tighten all cables too.

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