Wireless client "can't find DC" on startup: Event 1054

Problem: Wireless Windows XP sp2 client logs event 1054 from USERENV, "Can't
find domain
controller," every morning at startup, presumably due to a timing issue.
Group policy refresh is aborted as a result.

Configuration: Windows 2003 Std Server Active Directory domain with wired
and wireless XP sp2 clients. Problem does not occur with wired clients.
Gpupdate and similar tests work fine on the problem client after user login.

Solutions attempted
1) KB 304970: Use local policy on problem client to enable "Wait for
network" at startup. Error still occurs.
2) KB 298656: Specify IP of DNS server. Error still occurs.

Other suggestions, please? Thanks!

-Doug