There's quite a few discussions on this recently and i'm wondering why.
The frequency is increasing somehow.
One way is to flash the CC3000-patch file and see if it works! Seems to be the working solution based on the recent threads
The general troubleshooting guide i go through with 
users is:
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Chip antenna or U.fl
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Wifi type (Security, router make, SSID/password with funky characters)
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Status of LED (flashing green, orange/red etc)
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Factory reset followed by sending credentials over Wifi/USB
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Patch programming
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others