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Recently, my friend's PC came to a grinding halt. It was quite messy and the system was full of cruft so I decided to do a clean XP Professional install. The system is a Turion64-based HP laptop (Pavillon dv5000) and is a few years old. The original symptoms were extreme sluggishness and constant swapping, which I assumed was probably due to some malware and a few (useless) AV programs running at the same time.

I did a clean install and as I expected, it all went away. It worked all righ for about a month and suddenly it all came back. No new software was installed between then and now, the system was protected by Avast, it was pretty much just used for Word. Now it takes forever to boot, most operations take a long time, for example copying a file from a flash drive to disk makes the CPU jump to 100% with the disk thrashing constantly. The same happens when playing some video from YT in Firefox. I tried investigating with Process Explorer but it turns out that in such situations, 100% of the CPU is consumed by "Hardware Interrupts and DPCs". I've no idea how to work with that. I'd be most grateful for any suggestions. I'll probably have to reinstall XP again but I have no guarantee this won't happen again so I'm quite demotivated as you might imagine.


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How much RAM in the machine? – Linker3000 May 18 '11 at 23:19
Not much, just 1GB. But that was enough for word processing and basic web browsing until now. – neuviemeporte May 18 '11 at 23:24
up vote 3 down vote accepted

The high CPU utilization and high number of interrupts points to a likely use of PIO mode over DMA mode by the hard disk; some DVD drives and the like, usually work in PIO mode only. You might want to check whether the IDE channels are configured to use DMA mode, in the Windows Device Manager.

If you want more details on this, do check the Microsoft Support KB on what causes this issue. The hotfix is usually not needed; Windows forces the devices themselves start operating in PIO after certain failures, so switching the device to operate in DMA mode should usually resolve the problem.

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That's spot on, thanks! It's just that it isn't possible to switch the primary IDE channel "hard" to DMA, just "DMA if available" so it's just stuck in PIO. I'm also wondering where did these CRC errors come from in the first place to cause this and if there's something wrong with the hardware perhaps? – neuviemeporte May 18 '11 at 23:36
Hmm, interesting. I don't remember what I did when I encountered the issue. Maybe it was the hotfix, or maybe it was some configuration that I altered in the BIOS. Try the BIOS first, and then the hotfix. By the way, I encountered this issue after an improper shutdown; I had operated the PC as a server and shutdown it down via the power switch, but it really could be anything. If you're paranoid, you should switch on SMART monitoring. – Vineet Reynolds May 18 '11 at 23:39
I noticed that the KB article says it's possible to uninstall the ide channel's driver and reboot - it will be reinstalled and set to DMA by default. I guess I'll try the hotfix though to avoid this in the future. – neuviemeporte May 18 '11 at 23:42

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