jancg wrote: t need cygwin1.dll to work. Might this cause the strange behaviour? Absolutely. It tells me your target app is essentially a kind of Unix/Linux thingy, and CYGWIN has to do god knows what to make it behave (a bit) under Windows. There still might be a solution, however I don't know it; I'm unfamiliar with the CYGWIN + .NET combination. If the app is related to www.zebra.com by chance, you might ask them; they just might have run into this before and hold a solution. :) Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles] Nil Volentibus Arduum Please use <PRE> tags for code snippets, they preserve indentation, and improve readability.