Asterisk becomes unavailable every Sat. at 10AM

Hello,

I have a very generic installation of AsteriskNOW running in my office. Everything works fine during the week, but on Saturday morning, around 10AM the callers all of a sudden get busy signal. I restart the server but the lines don’t become available until ~1h after restart.

I use InPhonex for VoIP service.

Anybody has any ideas what could be wrong? What other info should I provide here to help solve this issue?

Thanks in advance!