I assume you have an executable in created with LabView 5.1. and now you updated Nidaq on the target machine.
Which version of windows are you using ?. with win98, Nidaq 7.3 will not run.
Make sure traditional Nidaq is installed.
In the list of supported devices, the PCI-6533 is listed and not the DAQCard 6533. It could be that it is not listed anymore. (It is not even listed in the unspported devices)
Also, the lastest version of Nidaq (traditional) may not be fully funtionally compatible with LV 5.1.1