Can't load drivers from the controlling PC

I have a Windows XP home network comprising two desktops and three laptops.
For the most part, it all works fine. One desktop has a printer attached
and shares that printer to the network. It also has a folder that it shares
to the network. The other computers do not have any printers, but they, too
share one folder of their own to the network. The desktops and one laptop
run Zone Alarm as a firewall, the other two laptops run Windows built-in
firewall. All Windows XPs are SP2.

The problem is when I wish to access either the printer or that desktop's
shared folder. I can see that systen in My Network Places on all machines.
I can see the printer and the shared folder. If I try to connect to the
printer, Windows tells me it's going to download the driver, then says
there's no driver compatible with the current Windows version. For the
folder share, I'm told I don't have permission. The printer driver IS a
Windows XP driver, so the error message is in error. As far as I can tell,
there is no permissions problem on the folder share; everything is
configured properly. Zone Alarm is configured to consider any PC on the
local network as trusted.

Going in the other direction, the shared folders on the other individual PCs
are fully accessible by the first desktop. Moreover, if I load the printer
driver manually on the individual machines, it prints through the first
desktop with no trouble.

I'm convinced there is an access permissions issue that doesn't allow access
to either the printer or folder as shares, but I can't see any differences
between the machines that successfully share their recources and the machine
that doesn't, although, as I say, a locally installed printer driver can
access the served printer just fine, even though the printer driver won't
load via the network. Any clues as to what to examine?
--
Brian Tillman