Our app at work is a huge project with over 3000 units, weighing in about 3.5 million lines of code.
...or at least it was when we were compiling it under D2007. We
It looks like it is a bug. The correct line number is still reported under Project | Information. See Nick's answer to a similar question.
Doesn't D2010 support generics? I think some of the libs have been replaced by generics, which could account for additional lines that appear to be parsed if it counts the "virtual" lines it's using.
I wonder if the handling of linefeeds/carriage returns to determine line count in the compiler progress area is getting befuddled somehow as a result of the Unicode internals.
Have you tried compiling in D2009 and seeing if that exhibits the same strange behaviour?
Could it be because it is more aggressive with inlining?