You don't remove any files from the Receipts folder unless you can't install a program of the same name (the system requires all receipts.) Then remove that particular receipt.
Did you open the Java 1.5 utility(preferences) found in your Utilities folder & tell it to use Java 1.5 as 1st preference? See
Setting up Java 1.5
If you haven't already, try deleting your LW preferences folder whilst LW is closed & found here /Users/your_username/Library/Preferences/LimeWire