The worst time your system bugs down is during peak hours. We have this enrollment thing going on an out of nothing ISA suddenly stops and refuses to start. ISA plays a major role in the system, it is where the SQL , DNS, DHCP and other important services are being published , thus a system without ISA in our system simply  halts the whole system. The only thing Windows is telling me is its error 213008 , which when searched in the almighty google , the main remedy is on reinstallation. I am having some hesitations on reinstalling it at first but i have to restore everything in 30 minutes. After several reading, i backed up my configuration, placed the installation CD on the drive and did the repair. In a matter of few minutes the system is back to where it was before the problem. Here is a link to the forum i was reading.