Aras reported that after he installed SourceTree, his Visual Studio 2010 builds (aka 'work') all started failing with the error:
LINK : fatal error LNK1123: failure during conversion to COFF: file invalid or corrupt
This is described in this thread: http://stackoverflow.com/questions/10888391/link-fatal-error-lnk1123-failure-during-conversion-to-coff-file-invalid-or-c
Both claim that Visual Studio SP1 fixes the issue, but Aras already had SP1 installed. He fixed it by uninstalling .Net 4.5 and re-installing .Net 4.0, but this means that SourceTree will no longer work.
This is a major show-stopping issue, we cannot allow the install of SourceTree to break a developer's working environment.
Note: this only affects C/C++ developers because the issue is in compilation of native resource files (.rc)