I am afraid I was the one that wasn't clear. You see, your wireless signal gets to your card from somewhere - it isn't conjured up out of thin air. That somewhere is a wireless router that is connected to an internet modem by a wire. If this router is too far away from your laptop, the signal quality will drop (just like cell phones and cell towers). When it drops low enough, you will get an interruption of the signal. This, I feel, is what you are hearing.
If you don't own a wireless router, then you are using someone else's - and they may not be close enough to you for good signal integrity.
It is sad but true: there is no free lunch. Wireless will get you mobile but to transfer as much information as internet radio requires, you need to have high frequency transmission. To have high frequency transmission, you have to be close to the transponder. More information = less distance. Perhaps there is a lower quality feed available from Pandora (I am not familiar with that particular site) that won't drop because you will have enough bandwidth to support it.
You may well have a good feed at one particular instant but that doesn't mean it is enough for all your music all the time. Feed quality is flaky - again, just like cell phones. If you are using someone else's router, then feed quality will depend on how many people are using the router at any one time. If there are too many people, you will get cuts in your music feed.
Arthur