Do you have the old installer saved? Yes, you can revert back to the older version if you want to!

Something you could try first, if you like, is delete LW's preferences folder when LW's properly closed. See point 3 here & also point 2 if you've used older versions of LW in the past (there could be a folder in either location).
Fixes for LimeWire
This will kill all of your settings within options, you'll have to go back through afterwards & reset things. If you're not sure of your settings, go through LW's tools > options & write them all down, so that you can reset things later.
In case you're using Vista: LimeWire Pref Folder in Vista

What's happening when you try to the older JRE version? Are you getting an error message? Have you tried using a different browser?