Could you check the Vista system log and see if there were any disk related errors? Also it’d be good to check what DMA speeds your drives are set at (if in ATA/IDE mode)…with enough errors Windows will keep reducing the speed grade until the hard drive is working in some PIO compatibilty mode. Real slow then.
I had something similar happen last year and it appeared to be a cable problem. The weird thing is all I had to do with take the cable out and reconnect it (or connected it to a different SATA port) and the recurring errors were gone. I’m still not convinced that was it but there are limits to my patience when troubleshooting hardware/software problems.
