|See the the info at the link in response 5.|
Also, if it's a wireless mouse, are you SURE you installed it properly on that system?
You are often required to install the drivers and associated programs BEFORE you plug in the module that plugs into the USB port.
If you didn't do that right, you may need to un-install the software for it listed in Add/Remove Programs in Control Panel, then install them the right way.
It is often a BAD idea to point Windows to the location of drivers for a device while booting with it connected the first time you have it connected, if you allow Windows to look for drivers and it doesn't find any, before software for it has been installed - the device will often NOT work correctly when you do that. CANCEL that, continue on to the desktop, then use the proper software installation program.
You are almost always informed when you install software that you are supposed to have a minimum of programs running when you install it, and are often also warned to disable your anti-malware software, in order for the software you are installing to install properly.
NOTE that when I installed drivers and associated programs for a friend's wireless mouse recently (a Logitech model) they would NOT install properly (the RIGHT button functions did not work properly) until I had disabled the resident component of his anti-virus software (Avast in his case, in 98SE - it can be disabled by disabling entries for it listed in msconfig - startup - other anti-malware including AVG 8 - it's Resident Shield - often can't have that disabled that way and must have the resident module disabled in the program itself).