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For whatever reason, my laptop has become massively slow on basically any operation. I cranked up the SysInternals Process Explorer and found that the CPU value of Interrupts goes through the roof on pretty much any operation.

What can I do to fix this?

Windows XP with all the latest patches.

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up vote 7 down vote accepted

Looks like you have a storage device that went off DMA access, check their properties.

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Specifically what should I check? How should I fix it? – AngryHacker Oct 7 '09 at 16:58
Right click on My Computer, Properties, Hardware tab, Device Manager, IDE ATA/ATAPI, Primary IDE Channel, Advanced Settings, Transfer Mode needs to be set to DMA. – Otavio Decio Oct 7 '09 at 17:12

I agree with ocdecio that it's probably your hard drive, and that's how you set it back to use DMA. Just wanted to add, though - Windows drops you from DMA to PIO access if it has trouble communicating with the drive. This can happen once in a while to anyone, for no particular reason (sunspots?) - but if you set if back to DMA, and then this happens again in a week or so, your drive is probably failing.

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a flaky or failing drive controller is also a potential cause of this, and can be easily mistaken for a failing drive. – quack quixote Oct 7 '09 at 17:55
So can a bad ribbon cable... that's a quick, cheap fix to try. – MT_Head Oct 7 '09 at 18:02
Even if you fix the underlying problem, Windows won't automatically re-enable DMA - you need to go through Device Manager as ocdecio suggested. And you have to reboot for the change to take effect. – MT_Head Oct 7 '09 at 18:04
@MT_Head very true on both points. i never remember to tell people to swap cables, i always have extras lying around if i need to swap one out, and i've rarely had them go bad on me. – quack quixote Oct 10 '09 at 11:09
i guess a solid takeaway is this: if Windows drops to PIO, try reenabling. if it doesn't work, or drops to PIO again before long, start looking for the cause (cable/drive/controller). – quack quixote Oct 10 '09 at 11:11

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