First, have you installed Sentinel?
If not, do it.
(IMO, it was a waste of money on pre-programming when the radio comes with free access to the RR database.)
Then look at your county and compare it to what is programmed into the scanner.
Now, briefly looking at MSWIN, it is P25 Phase II.
http://www.radioreference.com/apps/db/?sid=4879
P25 is digital.
I also see some very recent changes, which probably didn't get pre-programmed, if applicable to your area.
I also see that there is some encryption, which your scanner (and any commercial scanner) will not be able to receive.
OK: On analog, you get static when the signal is weak.
With digital, it is garbled when you are not getting the best signal.
Or, it's encrypted - then you are SOL.
It sounds like you are either in a weak signal area or you have interference of some kind - or encryption.
Cell tower close, Wifi, you name it can cause interference.
Get up on the highest hill.
Does it improve?