|You can find old versions of FrostWire on: http://www.oldapps.com/frostwire.php I'm using version 5.7.7 with no problems.
To drop back to version 5 from 6 requires some attention.
If you are NOT dropping back to version five from six, you probably will not need the revo uninstall step, or delete .frostwire5.
Before installing a version 5, I'd completely remove versions 6. Use revo, a free unintaller and use the most rigerous level of uninstall.
NOW: (for Win7. Other systems will have similar files)
From file explorer, navigate to your c:\users\YourAccount
(assuming your system drive is c:\") and delete the folder: .frostwire5
This forces a reinitialization of FrostWire, so you will have to answer the setup questions.
After a revo uninstall, you may or may not not find this folder.
Now, install the version 5 program that you have selected and hope for the best.
Until these problems are solved, your best option would be to install the version that was working best for you.
Remember to turn off automatic update!