You are damn right Erik! In one of the labs of my university they have given me a project about implementing a simple chat between two computers via RS-232. I had to do it using 80x86 assembly and Microsoft's DOS Assembler. I had borrowed an old laptop from a friend of mine that had Windows 2000, while mine had (and still has) Windows XP. I can tell you about the hell I faced! While the whole code seemed fine, the program behaved strangely enough to make me rewrite it many many times with different ways and techniques. I finally discoverd that the cause was Windows' NT Kernel and the way it treats DOS interupts... The bad thing was that I couldn't install some old version of Windows 9x or DOS to both of the computers or find some others that had such an OS... Anyway, the chat worked somehow and I finally managed to get a passing grade...

George