Sounds like it's one of two settings for your touch pad. There is likely a program installed on your computer for controlling the touch-pad settings.
When you say "hold the pointer over a link.." do you mean your finger is staying in one spot on the touch pad, or you put the pointer there, and then remove your finger.
If that is case, it could be the sensitivity setting is set too high for your liking.
Also, it seems like I have seen a setting in most Synaptics touchpad applications that say something about automatically opening an item if the cursor is left there... but I can't remember for sure.
If there is no touchpad/Synaptics in the task tray (where your clock is located), then try going to the Control Panel, and then looking under hardware - mouse..
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"If to err is human, then I must be some kind of human!" -Me