alright I have found the cause of our first problem.
Indeed, it is what I suspected. CB doesn't detect GCC correctly anymore. I already suspected this yesterday, and more precise I didn't trust the masterpath anymore. CB had detected C:\MinGW\bin instead of C:\MinGW.
Remove the \bin, and it will work OK.
I do remember some code will check to see if we are already in the bin dir, but apparently not the version checking.
Now checking if debugging works.
[EDIT] : debugging still fails on the laptop, but works on the PC :-(
[EDIT2] : fixed the debugging issue too : laptop was back on GDB 6.3, when upgrading to 6.6, it seems to work [very basic test on a Hello world console app].