Hey, this is easy to fix, im running amd64 on windows xp 64-bit as well and if u go to the mirc.exe and right click on it and select "propterties" click the "Compatibility" Tab. Then under Compatibility mode click the drop down box and select Windows 2000, and make sure it is checked to run in that mode. this should fix everything. click ok and run mirc.
poof. errors should go away they did for me
