I too am having this issue:
OS X 10.5.2 Macbook
Parallels 3.0 Build 5584
Fedora 8 i386 - all updates applied
Parallels Tools has been installed
Upon initial installation, the mouse clicks worked fine. However, the resolution was 800x600, so I manually changed it to 1280x800 in /etc/X11/xorg.conf, went to full screen and all looked fine. However, after the change, mouse clicks do not work.
Best Regards,
Tom