What is the make/model of the laptop and how old is it? Also, what type of wifi card do you have and how old is it? Does it go in a slot on the side or was it one that came inside the computer that you had to remove a panel to get to?
Most likely the card is either going out or you need to update the driver and wifi card software.
Are there any other odd things happening like:
-Computer not waking up from standby
-Computer not resuming from hibernate
-Computer shutting off randomly
-Computer not recognizing USB sticks or other USB devices when inserted
Since standby is a power state, you may need a BIOS update or you might actually have a power issue with the laptop itself.