I just installed 7.3 on my alternate PC. I currently am using 6.2 on my regular PC (both are windows). Every ePub I try and open with 7.3 (this does not happen with 6.2) generates an error about HTML files that are 'not well formed' and wants to fix the files. Since I've had no issues with any of these files I'm very reluctant to allow the fix and also very very reluctant to install 7.3 on my regular PC for daily use!