If you are having problems printing from Internet Explorer 7 under Windows Vista, check to see if you have AVG 8.0 installed. If so, get the latest version from http://free.grisoft.com. I did have build 8.0.101 and upgraded to build 8.0.138–everything works fine now.
I’ve also seen reports that it could be an error while running IE7 in Protected Mode. There’s a thread in the Microsoft forums about this.