?? "third anti-virus" ?? no-no!! One only runs ONE anti-virus at a time, running more than one can damage the computer. [as per Norton's]

If the AV program is an issue: disconnect from the internet; run a full scan; if all is well, turn it off. Then open Bryce and let the render work unrestricted. When it is finished remember to turn ON the AV before re-connecting to the web. It is for such complications that some of us have 2 computers. One is for "off-line only work" ... and then a laptop or something just for the internet.