Scott,
I have not tried it on VISTA yet and we can not really support it as we don't have the resources to do so but I would suggest you try the same things to rectify it that worked with XP. Have a look at the following post and see if any of the threads contained shed any light on the problem:
http://www.fly-euroharmony.com/forum/viewthread.php?tid=2179&page=1#pid16471As the Flight Logger is basically a Visual Basic program, it should work with Vista so long as you have the relevant DLL's installed and registered. Other things you might check.... Are you running FSX or FS2004? Do you have the correct version of FSUIPC installed?
Vista does have a lot of in built security which may be blocking the program, is Vista allowing it to access the interenet before the runtime error appears?
Both FSX or Vista can not be fully supported by us yet as we need all of the developers to upgrade to the relevant software which as I am sure you can understand, we can not all afford to do just yet. We will try and help where we can though.
Thanks