BillVette and PoliceFreak.. I think you guys nailed it. I didn't realize that I had to download the new system, I thought that simply updating it took care of everything. I downloaded it and Bucks is working good except I still have periods of silence, but they don't last too long and it's probably because of what radio3353 said... the new system will have some dropouts and missed transmissions when monitoring it using a 436HP.
Policefreak, however, Philly is still acting weird but different than the brief periods of silence that I'm experiencing in Bucks. The other day in Northeast Philly I was in a customer's house for six hours. The scanner sat on the washing machine for the entire time I was working and for three hours straight it was silent and then suddenly worked great for the next three hours!
I'm gonna wipe the scanner clean and download everything again. I too use sentinel.
Thanks again for all your help.