Citrix dropping connection, packets drop

We've had service for a few months but have had this issue every once in a while, lasts for a few days. We had service in a previous location with the old SMC modem and never had a problem, but since we got the new black Cisco?  Our 20 users at our main office get disconnected or freeze at times. I have run a continous pingtool and seem to be running at 8% drop rate which is horrible, tech support said all looks good from their end, they ping the gateway and their modem from their computer, all within the Comcast network, when I asked them if they could ping from the modem out they did but can only ping 4 packets and of course that is successful. Pinging from a command prompt does not fail as with the pingtool (Colasoft) probably because of a shorter time out or interpacket ping time. Anyone have any ideas or similar issues? These issues would not be a problem with visiting websites, but are with a always on connection like Citrix.