Multiple computers mysteriously slow down, not traceable to system resource

Question

Doesn't that title make me sound like a superstupiduser? I swear it isn't a stupid question.

I'm running into a scenario I haven't encountered before in an organizational peer to peer Windows network. Very informal network, low control, sloppy, some very crappy computers amongst better ones.

In the past few days I have had several reports from various staff that their computers began going ridiculously slow. It is true. Programs will either be totally fine, or going on random timeouts for minutes at a time, with no explanation. I have checked all of the obvious things I know:

• During these timeouts, there are no processes running up any CPU, extensive or unusual memory usage. In some cases I have a GB or more memory free, no page file, CPU running around 5%.

• I cannot trace this down to any active virus running, I have quarantined the computers down to the basic system processes as far as I can tell. I don't see any unusual programs running, unless it of course some virus has injected itself into a system process. Killing explorer.exe doesn't affect the timeouts.

• The speed even seems to extend to boot time when Windows starts up.

Keynote

Now normally, I would automatically attribute this to a hardware problem, such as a failing hard drive.

Look man, your computer is dying. It's terrible. Buy a new one.

However, the organization has had a few viruses that have crept in in the past week that I am stamping out, but these look relatively simple and are easy to kill.

But the main thing that is getting me is this is happening to several computers at once! And some of these computers are not bad at all! It definitely looks like a software-induced problem, however I cannot map it to any rogue processes or anything tangible, to my knowledge.

Question

Is there any way a virus could damage a computer to reproduce the above effects and dramatically slow it down, despite not appearing to use any system resources and without any active process running that I am aware of?

The only thing I could think of would be some program intentionally scrambling or fragmenting the file system so it is forced to work unreasonably hard for a simple task, or some other I/O manipulation. I haven't done too much diagnostics on I/O problems.

Nitty Gritty Details

The versions of windows running vary, though a majority are Windows XP, but this problem also reproduced on a Windows 7 laptop.

On what is timing out, its system-wide timeouts. For example, you press CONTROL-SHIFT-ESCAPE to start task manager, 20 seconds. Now you can move it around fine. And it behave fine. But you press 'Show processes for all users', and that takes 5 minutes. Totally random. It applies to vendor programs (such as office), or normal windows dialogs or programs, regardless of explorer.exe.

Answer 1

One thing you could try for the XP machines is to disable Windows Update. The algorithm used to calculate updates is exponential time. However you should see the svchost.exe at 100% utilization if this was the case. Trying this however will eliminate yet one more cause. Also, hope you're unplugging all those XP machines from the Internet come April 2014. End-of-life and Microsoft means it this time.

Answer 2

It sounds like you have already removed viruses, but I am picky about what I use. What exactly did you use to scan the computers? I use Malwarebytes typically. If the virus still seems to persist and you cannot rebuild the system, I would boot to a Kaspersky Live disk and scan with that. Make sure you update Kaspersky before scanning.

What programs are running slow? Do they require network connection? Have you tried re-installing the programs?

I understand that you say that the problem persists through several computers, but these are places I would look despite that.

Another possibility (I know this is most likely not the issue...) is temp files have built up. Have you tried using CCleaner? This is probably the least likely out of my suggestions to fix the issue...

If you say the problem persists across computers, the only thing I could think of in regards to that aspect is that the program that they are using is requiring network connection, whether that be to another computer on the network, a NAS on the network, or the internet. Perhaps this connection is getting bogged down or host machine is having issues.