Windows has an option to turn off the hard drive after a couple of minutes of inactivity. This is to save wear and tear on the drive and to ensure it's longetivity (kinda like the CD-ROM spinning down, or the monitor turning itself off). The drive will automatically turn itself back on (it will hang for a second or two while doing so) when data is needed so there's no need to worry. My secondary drive regularly turns itself off and spins back up when I need it. If you want to turn this feature off go into power options in the control panel (in Windows XP, I don't know about 98) and you can turn it off there.
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CPU: Intel Core 2 Quad Q9450 @ 2.66 Ghz (Yorkfield) Mobo: Intel DX48BT2 Memory: 2048 MB PC10600 DDR3 Videocard: PNY Geforce 9800 GX2 PCIe w/ 1024 MB GDDR3 Soundcard: On-board SigmaTel High Definition Audio Hard drive: 300 MB Maxtor & 1 TB Hitachi Optical drive: LG GGW-H20L (2x BD-R DL) OS: Microsoft Windows Vista (32-bit)