Has anyone encountered the following problem?

I am running M0n0wall 1.2b2 with a LAN and WAN nic.  Off the LAN nic I
have a Linksys WRT54G router running Sveasoft's latest firmware
(6.0rc1) that I connect to for wireless Internet access through the
M0n0wall.  Enabling the captive portal (non-https) with radius
authentication, I am able to authenticate successfully and browse the
net, check email, etc.

However, if I enable the captive portal with https and try to
authenticate through the portal, it authenticates me, and then loops
right back to the default authentication page.  The logout box comes
up, and I've confirmed that radius is successfully authenticating, but
I always end up at the default authentication page, and without any
Internet access.

The solution I've found is to use another old Linksys B access point
and the captive portal with https works just fine.  What I'm hoping
someone can answer is why the authentication loop when using the
WRT54g router, and why only under the https mode?  I've tried
disabling the MAC filtering option under the captive portal settings
to no avail.

Any help/info on this would be greatly appreciated.  I've got a
several WRT54G routers on order and would like to setup a mesh network
network on the M0n0wall LAN, assuming I can get the captive portal
https to co-operate.  Thanks.

-Sam