You could try mapping C:/D:/etc from the laptop as a network drive, and scanning it said mapped drive from the desktop that way, though I personally would be more than a little hesitant to do that, given you have not identified with what you have been infected (and therefore don't know the infection vector).
If it's eluding scans it may be either boot-sector (old school, but making a comeback) or rootkit (in which case it may be impossible to identify all security changes it's made). (There are probably more possibilities I can't think of.) I'd suggest trying a scan without being booted into Windows, from a bootable disk.
If you're an enterprise (corporate) customer, this is available to make a bootable scan disk:
How To Use the Symantec Endpoint Recovery Tool with the Latest Virus Definitions
http://www.symantec.com/docs/TECH131732
If you're a consumer customer, you have this option:
Downloading the Norton Bootable Recovery Tool for your Norton product
https://www-secure.symantec.com/norton-support/jsp/help-solutions.jsp?ct=us&docid=kb20100820160545EN_EndUserProfile_en_us&layout=Retail&lg=en&product=home&pvid=f-home&q=Norton+bootable+recovery+tool&version=1
Good luck...!
sandra