things to try depend on weather its a USB or Parallel port scanner.
for parallel port:
- check if you have other printer's software running in the task manager (next to the system clock), for example if you had old printer which you've physically disconnected, but did not uninstalled the software - it could conflict with new software.
- check if your parallel port in in enhanced mode, most scanners require it, especially printer/scanner combos. to check , shut down your PC, turn it on and watch the screen - before Windows starts loading usually there is a message "Press XX to enter setup" or some thing similar, where XX is F1 or F2 or F10 depending on your PC. Press the key its asking for when you see the message. you'll enter into BIOS setup tool, read little help screen, for navigation keys, it should be there. look for Parallel Port Mode, or Printer Port Mode item, you need to set it to ECP mode. if you don't have that option set it to EPP or enhanced. whatever it is, it should not be in Standard mode. Once you make a change, save chages and exit, let comuter to boot up to windows this time. It is important not to change anything else in BIOS setup uless you know what you're doing.
- also make sure you're not trying to print while its scanning, or to scan while its printing...