Yea... translating is hard in real-time, (ie. via Skype) and the conversation is temporary. It doesn't stay for those who come after and have the same problems. If you already have a friend here, you could PM them or, I notice people drop messages on Vormavs' profile asking to go 1 to 1 with him on stuff.
I do not know if he ever accepts, but I do know he isn't obliged to and that I would not, if I where him. Most of us find that we cannot afford to provide personal 1 to 1 support for things we develop and give away for free. It's not really fair to ask us to do so either, but if you do, I would certainly try to be *very* polite about it. :wink:
@The initial problem:-
You have both OS available for testing on similar hardware which is not virtual? (the client doesn't often work in a VM) There must be some problem with system APIs... however, no such problem typically presents. System APIs are included in the DLL by the compiler based on your copy of the MS SDK... so changing (perhaps "downgrade") the SDK and recompile.
Certainly, you should not build the DLL from Windows 7 / Server 2008R2 SDK if you expect it to work on XP. Rather, use XP / Server [strike]2008[/strike] (Edit: Typo... I meant 2003 of course :*:) SDK. ^_^
--- EDIT ---
AFAIK the Microsoft SDK Archive now only supports legacy systems as old as Windows Vista, or Server 2008 (non-R2). (which is part of what I was saying a while ago about support for XP ending, though of course the OS it's self has had it's support period extended several times)
If you are struggling to find an older SDK, I believe I have a few versions archived which would fit the bill. The fact is that while Windows 7 fully supports backwards compatibility with XP software, the Win 7 SDK makes no attempt to support older OS. So while your software should theoretically still work if you do not use APIs which are not included in older OS, there is no guarantee. Additionally, calling the current MSVC runtime libraries which have been "linked" against newer SDKs may well use APIs which are not in older OS without you explicitly calling them.
Again, if you only use the GCC toolchain (with any IDE) as Vormav does, they do not use any Microsoft SDK files, and the OS APIs they use are simply Win32 APIs and should be compatible with any NT OS from (I believe the minimum required Win32 OS is) version 4. For the most part, they also support Win9x. (which is also Windows version 4, but uses DOS instead of the NT kernel)Spoiler:

