Is the receiver directly connected to the PC or on an USB hub?
I have seen this problem before with the receiver connected to a hub. When connected directly to the PC port it ran OK.
Do you have another system to connect the receiver to and run RFreceiver to see if it works OK for a long time?
It is not expected that a receiver firmware update solves disconnect problems. It is more likely that the USB hardware in the interface or the driver is not OK.
Go to http://www.ftdichip.com/Drivers/VCP.htm
and check if you have the latest VCP driver version installed.