tbihn,
I assure you that our drivers are fully tested on all operating systems we support. It sounds like your installation of the driver was somehow corrupted. If you can get back into Windows, which it sounds like you can, please remove all NI drivers. You can do this by selecting "National Instruments Software" in Add/Remove Programs and then "Change." Once all drivers have been removed, you should no longer see the NI-PAL entry in Measurement and Automation Explorer (MAX) under "My System" -> "Sofware." At this point, please reinstall NI-DAQ 7.4. You may even want to try downloading it again in case the download itself was corrupt. Please reply to this thread if this does not work for you.
Regards,
Ryan V.
Applications Engineering
National Instruments
http://www.ni.com/support
Ryan Verret
Product Marketing Engineer
Signal Generators
National Instruments