"Freeze" is probably too simplistically phrased, but I stand by my experience of an annual failure rate of the total unit system, not just one screen. After the first failure (which "will never happen") management in their wisdom decreed that we stop all movements and close the airport until it works again. We quickly found some disgarded strip holders and got a new strip printing system. Now we have to stop all movements until the back-up system is up and running. If I recall correctly the back-up system also failed last time. What management can't or won't understand is that it is dangerous to remove a busy airport with minimally fuelled aircraft holding to land and limited alternates in the area - it may look good to their safety accountabilities, but it puts all of the other ATCOs, pilots and passengers at risk.
In answer to the question we still have radar and limited flight plans available, but failure of the electric strips requires that all movements are stopped. I stand to be corrected, but believe here are two servers on the unit which run our strips and failure of both leads to all screens failing. We have been told that each unit runs independently, but I could swear that at least one of our failures coincided with failures at our neighbouring units and that it was only its brevity that stopped the nightmare of all DEST and ALTN being closed at the same time. It does seem credible that the same system at different units running with the same corrupt data could fail at the same time.