error: the number of chars is above 500, please limit the number to 500 or less.

Some more info: once I input the text the couner shows actual number of chars. Then I hit SUBMIT, after the server returns the page the number of chars always 391. I tried to input 385, 455, 470 chars - after submitting it shows 391 below the text field.
Strange. I see it on localhost also.

I found another fact:
When I input latin chars - it works fine with 495 chars or so.
Once I substitute a dozen of latin chars out of 495 with cyrillic the error appears and the above described symptoms also appears.

It looks this line is responsible for calculating chars number on the server.
$current_body_length = strlen(trim($node->body));
I do not see why it should behave buggy with cyrillic.
Any ideas?

Can anyone share his knowlede abt it?

Tried everything, all in vain. Is there anybody out there?