Since it does not fit physically on the card reader of your computer ,then it's the reader does not support memory stick pro duo card.
Sony makes proprietary, non-standard memory cards.
But it's an easy workaround, you can go to your local computer store and purchase a USB memory card reader that supports reading Memory Stick PRO Duo cards.
It's called "USB memory stick pro duo adapter". You can also click here to buy online for under $10: