Computer is an old Dell Dimension 4500 desktop, mouse is the original that came with computer. OS is WinXP. Issue: Intellimouse clicks "work" fine (can hover, highlight, bring up query menus, etc.), then suddenly all clicks cease to register in computing environment. Cursor hovering is fine, however. Rapidly right- and left-clicking for a few seconds restores function temporarily, so clicks will "work" again, but only for a limited time. Mouse is firmly plugged into CPU tower. There are no cursor movement problems. Inside of mouse is gunk-free.