"Do you mean that the first character is corrupted or that an additional character is transmitted before your string? "

The string should begin with this "WEXP52..." instead it appeared something like this "***EXP52..." with *** are unpredictable.

"I also advise you not to use hyperterminal. I am aware of one fairly subtle bug in the XP version that WILL make you think your code or hardware is in error when it is not. Use any other terminal emulator, it is certain to be better. "

This is interesting :) I'll check it out asap.
I have minicom installed... oops I have to switch OS.