Hi Andrei, >> However could it be so bad that 400 mHz XScale hangs for a minute? << I would not think so. I haven't seen anything like this, but my projects have been smaller than the one that you have described. This sounds more like some sort of dead-lock. Do any of your worker threads share data or depend on shared objects? Perhaps something is going on there? Dick Richard Grier (Microsoft MVP - Visual Basic) Hard & Software 12962 West Louisiana Avenue Lakewood, CO 80228 303-986-2179 (voice) 303-593-9315 (fax) Author of Visual Basic Programmer's Guide to Serial Communications, 4th Edition ISBN 1-890422-28-2 (391 pages) published July 2004. For faster service, contact the publisher at http://www.mabry.com/vbpgser4<http://www.mabry.com/vbpgser4>.