I've customised nicklist to show ignored,idle60,idle30,@,%,+,- (sorted by prior.) nicks in different colors...

When connected to one server all is ok.
But when I connect to second server colors are screwed... :|
So I think i'ts a bug

how are those colors screwed?

/me sees nick colors right on multiple servers, maybe something is wrong with my eyes then??

Look at his eyes - He's probably in an internet cafe and looking at mIRCs either side of him hehe.

Colors were reset also when I used /hop command...
I was idle for more than 26Hrs but nick was colored in opcolor. Why?
Same happens when I make second connection to server.

IF you /hop'ped then yes, the idle related colours would be gone because as far as mIRC knows everyone on the channel could have said something in the split-second you were gone.

As for a second server connection, that should be totally independent, even if you're connected to the same server and on the same channel.

Are you sure you're not using any custom displays? Maybe you should check your scripts for on INPUT's and on TEXT's

Yes I'm sure.
I don't have any scripted TEXT, INPUT events.

As far as I can tell, the colors in mirc are updated apon joins, parts, etc. When the user list is updated, mirc uses the default color scheme. The only think I would recommend is making a timer, or indeed going with on text and on join events to 'refresh' the nicklist as it changes. If you join a channel, then the script (or I assume you are doing some sort of a /cline) wille xecute. When a user joines after you, is mode changed, or parts the nicklist itself is colors according to your mIRC preferences..

Maybe I am wrong in assuming that you did infact use another method then /cline, but as far as I can see try making a timer, or on mode/join/part event triggers.