one of two computers wont handshake?

Where, What did I miss? Please.

two computers both with WinXP Pro.
Both attached to Router (D-link.)
Both computers have Allow to share for HD and Printer. and indicate in Internet connections.
Both computer firewall (Zone Alarm have trusted zone.

Main computer (HP) recognizes the other (Acer) and all files and printer.

Acer blocked out to HP? Where.
Even when I close Zone Alarm it still says "does not have permission"

Exception... It will recognize Ink Jet Printer Only, not Laser and/or files
on HP!

I have gone over repeatedly. Checked properties for sharing, all activated.

Where Oh Where? Is permission not activated.