Until yesterday I was using Avira as my anti-virus s/ware. Over time I had noticed my laptop had been running more slowly and this week it was particularly bad with excessive CPU use and disk access.
It occurred to me it was possibly virus related yet scans with Avira and other anti-malware gave a clean report. When I looked at other options I discovered that MS Windows defender was getting good reviews so I ditched Avira to try it.
After a full scan of my device, offline and taking nearly 7 hours, Defender reported the presence a severe trojan called
swf/infpotok and enabled me to remove it. After starting my laptop this morning it's now lightning fast!
It seems Avira struggles to deal with this threat.
