One other thing to try if you are using GPO to set the default printer: There's a hotfix rollup out there that for whatever reason isn't being publicized much (I guess because it's a hotfix), but addresses a bunch of GPO and slow startup issues. Since applying this we've had substantially fewer instances of the default printer not being set properly.
Here's the link to the hotfix: http://blogs.technet.com/b/askpfeplat/archive/2013/03/12/slow-boot-slow-login-sbsl-hotfix-rollup-for-windows-7-and-serve…
Geoff