I have no problem scanning with my vacuum tube stereo playing, but when I tried to print and scan at the same time, my computer (Windows 98) didn't like it at all. Windows 2000 might do better.
The red streak is an all-too-common problem, apparently worse when the scanner gets warm. If it persists, return it. I haven't experienced it, but it sounds like a defect. Bob Atkins (photo.net nature forum) experienced it and returned his scanner.
I'm having trouble making SCSI work at all (I might have damaged something), and I've heard it isn't that much faster. It only affects data transfer, not actual scan time or dust removal calculation.
Good luck!