Most likely the cause is:
1. Bad usb/thumb drive - buy from Best Buy, avoid Amazon
2. Overheating - use extension cable or SD card inside adapter (what I've been using successfully for 2 years) though the former will likely work better
3. Lately, Live TV Pause doesn't work well if I have bad reception so make sure the signal is both good and can't be disturbed.
4. Make sure you have latest firmware.
5. Doesn't work with the web channels
I'd start by being sure it's not 1 & 2. For #3, consider that you might have a lot of static interfering with the signal.