For the 3 past weeks Sunday morning CET I don't get any confirmations for hours, and then later they tick in. Block rewards, MH/s are what they should be and the blocks are not longer than they normally are. I'm not feeling cheated. However this pause in inflow of coins has a great impact on the market at MTGOX. The price soars for an hour, and all the big players cash out and dropping the exchange rate in the process. If you are doing maintenance, or rebooting servers whatever, you might think about doing it on some kind of rotation. These shocks in the market. Scares the commercial users of bitcoins away, and destroys trust in bitcoin. We are trying to build a better economy here, not trying to get stinking rich.
On second thought, maybe a lot of people shut down their computers Saturday evening EST to attend their non bitcoin related activities, and the P2P and the remaining wallets gets overloaded with the transactions of the day? The advise would then be to leave your wallet running 24/7, maybe an extra one without money, if you are afraid of trojans!
Can someone explain this 2-4 hours break once a week?