A couple of restarts a day in a shared hosting environment is nothing much at all and I would expect to see even more than that. Your portal will be in a pool with any number of other sites and it's probably restarting for reasons beyond your control.
It's not really a big issue.. just have the site pinged every 15 minutes by Host Tracker so that it gets up an running again as soon as possible after shutting down. Of course, if the site hasn't got that much traffic anyways then the host would certainly rather it wasn't loaded and using up ram.
The only way out of it is to try and get your own dedicated app pool... which they may not let you have... or get VPS hosting with your own dedicated resources.
Rob