For the network.
Weak signal or interference from something like an IR extender, cordless phone, TV retransmitter, etc...
Routing problem due to the IP address the printer was assigned (maybe it once belonged to something else the PC is set to connect to).
Printer drivers may talk differently to an IP address port as opposed to a hardwired USB port.
As far as the power issue goes, I don't know if yours has an interface on it that tells you when it is "Warming Up" or "Getting Ready". If it does, then watch that and see if it is displaying that for the period that the program is frozen while possibly waiting for an "Okay, ready to go" response from the printer.
I've had a few service calls for small lasers and I have an HP one myself. The problem I am called to fix is that they blow the circuit breaker every time that you print because the power draw to heat them up is huge. You could also add trying it in another electrical outlet that is on a different circuit than the one you are currently using
That's a shot in the dark.
It really sounds like the programs are waiting for a response from the printer and any changes made in the program during that wait time could cause corruption or catastrophic failure in some circumstances. So, in order to prevent that from happening, it blocks any user input (freezes) until it is safe.