I've solved the mystery about Silverfast preview. It was a hardware issue. My monitor has completely died. To confirm, I hooked up a spare monitor to same graphics card and cable, and Silverfast worked OK. So I need to figure out what monitor to buy ASAP. Any help welcomed.
I'm having some video problems with my Silverfast Ai Studio software, and I'm looking at all possible causes. Oddly enough, the Silverfast software has been working very nicely since I bought it a couple months ago, and then the preview quit working for both scanners (Plustek 7500i and Epson V500). The preview pane remains solid black after a Prescan. If I blindly scan, I'll get a scanned image. And if I use the manufacturer's scan interface I get a preview and scan with no problem. It's only Silverfast that suddenly developed this weird problem. Posted a query with Silverfast tech support 24hrs ago, but no reply yet. I don't really expect anything useful from them, but one never knows.
On the same day that Silverfast began acting up, something weird happened with my display. A wide vertical section of the screen suddenly became distorted and vertically banded and unusable. Rebooting didn't solve anything, and only after wiggling power and video cables did it go away. I had to assume it was a loose video cable. However, the timing made me suspicious that I might have a failing graphics adapter or display.
So... I'm thinking about what I might get if I need to replace my 19" NEC MultiSync LCD 1980FXi. I bought this monitor because it was of a type that was supposed to be good for photo editing, as well as other general purpose use.
If I have to replace this monitor, what might be a good 19" monitor that would be decent for photo editing? I'm not a professional and don't need/can't afford something like an Eizo. I love the 19" size because it runs at a lower resolution compared to screen size, making it much more user-friendly.