Thanks, but tried about 5-6 times already.
How about a simple Flex app as opposed to an AIR app? Sometimes you need to change the line in your AIR app descriptor file:
If yours says 1.0 or something, try changing it to 1.5.
Try giving the FlexBuilder install directory full permissions for the current user.
Also check if certain files in the SDK directory aren't blocked.
To do so check files' properties in the following directory:
C:\Program Files (x86)\Adobe\Flex Builder 3\sdks\[VERSION]\bin
C:\Program Files\Adobe\Flex Builder 3\sdks\[VERSION]\bin
Where [VERSION] is the sdk version (e.g. 3.0.0)
Right click any .exe and .bat file you see in that directory, select properties.
At the bottom of the properties dialog it may say something along these lines:
This file came from another computer and might be blocked to help protect this computer
If that is the case, click the "deblock" button next to it.
If you have multiple SDK's installed, repeat the above.
I found the problem, my localhost was incorrectly defined, setting the debugger to use 127.0.0.1 or fixing the localhost entry sorted it. Thanks for your time.