I'm experience the similar situation. But I found out that it just takes long time for the variables to come up. If you wait for maybe 2 minutes then the values of the variables are shown and you can continue to debug.
I didn't have this problem with the old 2007.1 version, but now with 2008.1 and MINGW I have it consistantly. If using the VC compiler and debugger then everything works smooth.