Have an older computer with some weird connections. The old 5-pin keyboard connectors and like two, seemingly suspect, mouse plugins. Now, the issue is here that the client cannot get their mouse to work and I'm not sure where to even plug the thing in. Running Windows 98. Ridden with spyware, but I guess they really only want the mouse working, and quite frankly, that's all I'm really willing to do with this computer. If it's a spyware issue, the damn computer doesn't even have an ethernet card and I really don't feel like swapping one in, if there's even PCI slots to do so. I'll have to open it up later, but given the information now, anyone have any ideas?

It's probably be a good idea to open the case and check the internal connections. The other port may be an infra-red port. Or download the motherboard manual. If you can't get it figured out, spend $5 on a serial mouse. (Don't use one of the PS/2-serial adapters)

The mouse is probably connected to a serial port. Usually one serial port was a 9 pin connector and the other was a 25 pin connector. If the mouse is defective you should be able to find a serial mouse somewhere. If the 9 pin serial port is defective, you can probably find a 25-9 pin adapter.

Nihilive, you need to confirm exactly which port is being used for the mouse. As Ham suggests it sounds like one of the COM ports. Often with older machines a driver was loaded that enabed to the mouse to work. See if you can find refernce to it in config.sys or autoexec.bat. Quite possibly, if it is in a folder there will be a test program there as well. But I find these programs are best used running under dos. Good Luck - Keep us posted.