1/ what mouse type and manufacturer are you trying to use?
2/ corrupt drivers can often cause this behavior,
3/ go into the control panel, then system, then hardware/then device manager,select the "mice and other pointing devices" delete any mouse device showing. then restart windows should then find the device and install the drivers stored in your computer.
4/ if it is a microsoft intellipoint mouse you can download he latest drivers from here :-
http://www.microsoft.com/downloads/details.aspx?FamilyID=ea22bd62-4873-406a-bbbe-c587d35a53bf&DisplayLang=en then go into the control panel, then system, then hardware/then device manager,select the "mice and other pointing devices" delete any mouse device showing.
then install the new driver and restart.