Attachment names in Russian are truncated

Hi all!

When i send message to RT 4.0 the name of attached file in Russian
language is truncated (e.g. Письмо;). Origin name of attachment is
"Письмо для меня.doc". In previous version of RT i used (3.8.9) there
was not such kind of problem.
This problem occurs not always. For example when i send message with
attachment from Yahoo RT saves attachment name correctly.
How i can troubleshoot this problem?

Thank you