>It doesn't make any sense. Why unused local variables would have such effect? If you can come up with repro coude, submit it as a bug to MS.

Yes, I have a repro code. But, that requires me to send the entire framework as this has to be executed as is. What I have found is that the number of lines is a factor. If I add more lines in another module which is not even executed up to that point, it could trigger the bug on the next build. So, it was working ok for a while but when I started to add more code elsewhere, it started to go like that again. This is something I have found in the last year. In some occasions, if I don't touch the code and just recompile, it will work ok. If the size of a certain PRG, for exemple, increases, I will face the bug.