Hey guys, I've been looking into this, so forgive me if you've been through this before, but I'm trying to find out more info.
When you say "it is down" are you seeing it get stuck on the validating login or does it display an error?
I've seen it personally get stuck on the validating login and then all of a sudden after trying again, it gets through. I've checked the server and there are no exception getting thrown and it appears the server apps are actually up (other than the Friday morning reboot). Looking at the java console when this happens, it appears it is not actually connecting to the server, or at least not able to send the actual login message. When this happens, there is no login acknowledgement and it just sits there waiting to "validate login". This indicates something funky on the client and I would suspect it has something to do with the Java Runtime.
That's not to say there are not other issues, but this is the most likely cause for this specific behavior.
So...
1. I need to verify that getting stuck on "validating login" is what people are referring to most often when they say the server is down. If there are other issues can you let me know. The more info we have on exactly what is happening, the better.
2. If someone is encountering this problem consistently, can you download the latest Java Runtime by opening the Java window in your Control Panel and then clicking the "Update" button on the bottom of the Update tab? See if that makes any difference. The automatic Java update doesn't always pick up the latest version, so going through this process will ensure it is the latest (which I think is something like build 20 at this time).