Cdphili,
I too had issues with the same video card on a Sony Vaio Z790 running Windows 7 Enterprise 64 bit. While Nvidia had the updated drivers, they were not compatible with the Sony notebook. It took until the official release of Windows 7 and some help from the folks at http://www.notebookforums.com to get my drivers up to date, but once they were updated, all known issues were corrected. The Nvidia card you mention is the only card we have run across that exhibits issues with ProDiscover.
Please identify if you are using the most up to date video driver for your operating system from the Nvidia web site. If you are and still have issues, please let us know which make/model computer you are using and the installed operating system, so we can look into the issue.