I have versions .122 and .124a, yours is most likely close to the same tho. Go into your MAME folder and look for a file called mame.ini, open that in notepad and you should see an entery that looks like this: mouse 0 - change the zero to a 1. If you don't see the mame.ini file, goto command line and from your mame directory type - 'mame -cc'. That will create the ini file.
Hope this helps.