As a proactive measure, I switch on two computer rooms every morning and switch them off at night. This allows me to give the machines a twice daily once-over.
My tech does the same to another two computer rooms.
We assume the ICT Teacher is competent enough to do the same to his teaching room (although he is new, and we do have to keep asking "is it all okay?").
We ignore the other 6 computer rooms, as we're trying to make the point we're understaffed... and they're actually based within specific departments.
Until my McAfee EPO server failed recently, I would check to see if machines reporting in, and check up on anything that hadn't reported in within 90 days.
Being able to know that there is one or two machines dead (or dying) in a room, just means we can sort them that day, or the next. 'course it does appear to be the same machines causing issues everytime.
Since we fill the printers in the IT rooms I generally go through twice a day through all 3 IT rooms and the library area, and it's usually obvious if a machine is poorly, or a keyboard broken or such.
Computers in other classrooms we only get to see if we're called out to fix them (or something in the vicinity and notice it in passing).
We had a room with an IWB, and the computer linked to it was replaced, but I was distracted halfway through and had to leave the job of installing the drivers and connecting the VGA lead, until later.
This was in September - it was the following July until someone reported it, and then "I've GOT to have it for this lesson! I use it all the time!". So, er, you use it all the time yet we never actually plugged it in? And it's been like this for almost a year and you've not reported it?
One of those moments where I just say nothing and walk away to avoid saying something I'll later regret!