I have a new olympus sz 15... after chargiong and downloading pictures... it is frozen... none of the buttons work... only the picture button does, somewhat - it will change the screen whgile holdin down but will not take a picture... i have pulled and replaced the battery... dont know what to do???

When you put in an USB cable, the camera starts charging the battery, or when some signals come from the computer it knows it needs to send pictures you the computer and wait till it gets the order to do so.
Only for the more professional camera's there are programs so you also can use the camera in combination with a computer. Professionals buy these software and use it in a studio with the camera switched to live view.
When you want to use the camera, never leave something in the USB connector and make sure it is free from debris.
Any connection in the USB connector, can "fake" a computer or charger connection, and the camera waits till it gets a commend from that port. It won't listen to any command on any button.
When you are sure the connector is free and clean, remove the battery again and reinsert it.
If the error comes back, return the camera (or visit a Olympus certified repair centre) because it must be a warranty issue.