An Insteon network can be very reliable but it may take some work to clean up the powerline before reaching that point. PC and UPS power supplies are common sources of Insteon signal attenuation. Smarthome makes a FilterLinc which isolates devices from the powerline preventing Insteon signal attenuation. FilterLincs also prevent electrical noise being generated by an appliance from reaching the powerline. Either situation, signal attenuation or signal noise will reduce the reliability of powerlline communication. Because an EZSrve/EZBridge is often plugged into the same circuit as the PC/UPS, it is not uncommon to need a FilterLinc to isolate a PC/UPS from the powerline. Other devices, such as TVs can be sources of signal attenuation, some CFL devices as well as cell phone battery charges can be sources of noise. If you scan through the Smarthome forum you will find many cases where FilterLincs were required to eliminate signal attenuation and/or noise.
For an EZSrve/EZBridge PLM to receive Group messages from Insteon devices, and therefore be aware of a device status, it is necessary for the EZSrve/EZBridge to be linked as a responder to the particular device. It sounds like some of the devices are not linked as a responder. Without this link you would be able to control a device from EZSrve/EZBridge with Direct commands but Group commands issued by the devices themselves would not be recognized and passed to EZSrve/EZBridge through the PLM. This will also prevent Macros from being triggered by specific device status changes such as On or Off. When getting “no status” for a particular device intermittently it sounds like you have powerline issues that will have to be resolved before you can expect reliable Insteon communication.
What Browser (and level) are you using? I run with IE 7 on XP SP3, using both an EZSrve and an EZBridge running Ver 01.60 and do not see the hang up or lack of screen buttons you are describing.