Hello,
What tool are you using to debug? I've had problems with Interdev and with VS 2008 in that the break points aren't where they appear to be. I believe that there's some kind of mismatch due to double-byte characters.
The work-around that I used for this was to put a break point on a bunch of lines, sometimes every line in the file! This is because I couldn't tell which line was which in the debugger. I could then step through my code and tell which line I was actually on, by setting watches for different variables, and seeing their value change when they were assigned.
With IIS7 and VS 2008 SP1, it seems that the character set issues are resolved, but I'm running into other problems getting my middle tier COM+ components to work on IIS7.
-Eric