The way to load tables from the command line has changed - the "-" before passed table name is no longer used. It used to work like this (substitute your paths and filenames, of course):
Code:
"C:\Visual Pinball\VPinball.exe" /Play -"%1"
But now it should read:
Code:
"C:\Visual Pinball\VPinball.exe" /Play "%1"
You can change this in My Computer > Tools > Folder Options > File Types, select VPT, click Advanced, then Edit each of the Actions listed and change the "Application used to perform action".
(Those instructions are for XP, they're probably different under Vista.)