Which NovaScan product do you have? The one that I know is the Novoscan 4000 which is listed for XP or Vista (32- or 64-bit). Since the drivers do change over time, sometimes the old software doesn't work directly.
The software is here:
http://www.braun-phototechnik.de/en/downloads/Software-Treiber/~did.8~nm.15~nc.21/BRAUN-NOVOSCAN.html . Get the correct version for your computer - 32-bit or 64-bit. Unfortunately, I don't see any OS version labels here.
Unfortunately, Microsoft has no information on the compatibility of the Braun NovoScan products.
http://www.microsoft.com/windows/compatibility/windows-7/en-us/Search.aspx?l=en-us&type=Hardware&s=Braun%20NovoScan .
If you continue to have problems, there are two options to try. 1) Install with the compatibility mode. This may work. 2) Install to a virtual computer with an OS that you know is compatible (or a second computer with that OS).
For item 1). Download the software or use the CD. Right click on the exe file and choose Properties. Click on the Compatibility Tab and set it to run as compatible with an older version of Windows. Save the setting by clicking OK. Next right click again on the exe file and choose Run as Administrator.
For option 2) If you have Win7 Pro or Ultimate there is a free option. Download and install Microsoft's Virtual PC and then the XP mode. Otherwise you need a virtual computer program and a licensed version of an older version of XP. Install the scanner inside that "computer". The only issue will be that files can't be shared between the two "machines" directly. You will need to save files to external media (or optical media) to share them. Also peripherals (like printers) can only be installed to one "machine" at a time.
I hope this helps.
Cindy Wells
(I found some other sites that claimed to have Novoscan drivers but the trustworthiness of those sites are unclear to me. They were found by Google.)