Let start from begining:

1. I have upgrade CS 2.0-->2.1 (works just fine without any problems) .NET 1.1

2. I have install CuteChat 3.0 for CS 2.1 (works fine. Procedure is not complicated)

3. I have do that last night abot 23.00, test it CS and chat modeul works ok

4. This morning ahhhh  "we are unable to serve your......"

5. My site is suport for our students so it must works, so I quickly Restore database and ovewrite web directory with last night content before installing CS and CommunityServer works again

6. But before db restore I have run this SQL

select * from dbo.cs_Exceptions
order by DateLastOccurred DESC

I hoticed a LOT od errors between 03.00 - 08.00 I hope that I have remeberd "CommunityServer Catastrophic error......" I never see this before and I use CS from version 1.0

7. I have again instal CuteChat 3.0 for CS and for now it works great..but....I not shore what is reason for a problem. I must say that Windows 2003 server had make automatic update about 03.00 this morning..so one of the suspect is that. I dont know is this some security issue with this (hacked site). I hope that someone will help me with this

For now I do monitoring system and cs_Exceptions table

Thanks for any replay!