I am pleased Tilly because I was about to post the following :-
//Tilly....I have given further thoughts to your problem and have come to a few conclusions on the issues concerned. If I am proceeding along the wrong lines then I feel sure that the Ed or a respected Techie will correct my beliefs.
1.) You have been subjected to a Virus which appears to have arrived via AB.
2.) The virus can be linked to a fake 'up-date' for Java.
3.) It is possible that you already had Java installed in your Laptop but Did Not really require it. Anyway, a complete 'clean-out' is now required.
I suggest you proceed as follows :-
a.) Check to see if Java is in your programmes and, if so, uninstall it. :-
http://www.java.com/en/download/help/uninstall_java.xml
b.) Give scan with your AVG: Followed by Malwarebytes.
Then if it is necessary for you to have Java to play on-line games or for using certain Internet sites, then download and reinstall from the official site which is :-
http://www.java.com/en/
Incidentally....I get along without Java because nowadays there are very few sites that require it.//
Hans.