I just downloaded the latest release of MAME. For some reason, with this version, and previous versions of MAME, the mouse is labeled for the Analog input, but for Inc and Dec, is labeled as left and right, but I cannot change the Inc and Dec to use the mouse. Older MAME versions would work with the mouse, but lately the past 3 MAME releases will not allow me to use my mouse in the program.
The mouse itself is a Microsoft USB mouse, O/S is XP Pro SP3, Intel Pentium Core 2 Quad 2.8ghz x4 with 4gb ram running on a 320gb hard drive. Video card is Nvidia Nforce 1gb. The mouse I have no problems with in any other program and its about 3 months old, the computer is about 2 weeks old.