Calibre/anti virus problem

[nicky53]

Hi I have an odd problem and I am hoping there is a solution. A couple of days ago I changed anti virus s/w to Bitdefender. However this morning when opened Calibre it wanted to update which I did. When I opened Calibre after updating it, bitdefender jumped in and blocking it opening a file (I think library file #5), Bitd asked me if I wanted to set up an exemption, which I did. When I opened Calibre again it said that particular file was corrupted and went to backups. All appeared good until looked at Calibre, I normally have app. 1400 books currently it is showing only 170 books - where do I start please?