A hard reboot may help. From the FAQ, here are the important numbers. What are yours?
7. The signal strength information is on page 5. You need to look at the QAM side. The "level" should be between -10 and +10, with zero being about optimum (for digital stations). If the level is below -10, you'll see the number change to "orange" for "warning". You may have to change splitters, cable, etc to rectify the situation. Call your service provider and they'll usually rectify with better splitters, cable, possibly an amp or a new "drop" into your house. (Interestingly, many of us have found that the SA8300HD gives "false" signal strength readings of -20. If all other readings are "normal" and you've got no other issues, do not worry about a -20 reading on the SA8300HD)
8. On the same page is the Signal/Noise ratio. The S/N ratio is good if it’s at about 35 dB or higher, although a good HD signal can be received with slightly lower numbers. If your S/N is around 30-32 (or less) though, that could be a source of problems.