Thank you for your quick replies, changing to WIA, made it!
Now it works fine with my HP scanner.

Thanks,
Mat

Hello! Today I installed PaperScan Free Edition v1.8.1, but when I try to scan, it doesn't find my scanner. It's a HP Photosmart C4580 All In One printer and scanner connected over usb. The pc is running Windows 7 and the scan and fax software in Win7 finds the scanner. PaperScan only finds two devi...