We have Avast Pro 5.1.889 and we use Incredibuild 3.20 on Windows Vista SP2 x32 PC.
Since upgrade to 5.1.889 when we launch a build with Incredibuild from the coordinator PC, a crash in "cl.exe" appear.
I tried to disable totally Avast, but no luck. After uninstalling Avast the problem was gone.
I tried to reinstall Avast (directly 5.1.889, so no update issues involved) and the problem returned.
With 5.0.667 there was no problems.