VS 2008 or MSBuild Bug

While i was trying to add a reference to an external project I came accross the following error while compiling a WPF project in xaml:

Error 1 Unknown build error, ''clr-namespace:[MyNameSpace]' mapping URI is not valid. Line 4 Position 21.'

After a bit of research I realised the problem was with the Assembly Name having spaces within.
To fix this right click the project and change the assembly name so that there are no spaces.