"We contacted all of our users to let them know about our fix to the ProActiv situation this morning," Travis Witteveen, chief operating officer of Avira, said in a statement to CNET. "The issue only arose on 32-bit Windows premium, suite and professional products, whom had ProActiv turned on (by default ProActiv is an opt-in feature, so the infected base was not the entire base). We do not know the exact number of those impacted, but we are confident we reacted immediately and communicated thoroughly."