Try a factory reset.
There should be some instructions within the TV's manual. Maybe in a troubleshooting section.
One site mentioned pushing in and holding the power button for 5 seconds to reset the TV.
Google "Toshiba 32D3454DB TV Factory Reset". You will find other procedures/methods.
One thing to remember is that sometimes wireless devices may take some time to search about and find or otherwise detect nearby wireless networks. That may be what is happening during the "screen locks".
Not sure what search time would/could be considered "too long". Maybe the TV is just in a less than favorable location with respect to transmitting and/or receiving a wireless signal. Does not take much signal degradation to cause a...