Franchi and any others who have been infected by "ransomware" here is a way to get rid of it.
I had this problem over the Christmas break, I think it got into my computer via a Java update.
Go to this site and follow the first part:
http://www.spyware-experts.com/system-tool-removal/?gclid=COHX96KyhqYCFQgHbAodvy7logOnce you get the screen shown, try going to "Last Good Configuration". If the computer opens as normal problem solved. If not re-boot and go to "Safe Mode with Networking".
Your computer will boot into your desk top but will appear a bit strange, do not worry. You will get a help pop up, look for "system restore" Open "system restore" and follow instructions, you will have to go to a restore point date that precedes your infection by the ransomware.
This should work, it worked for me. I wouldn't worry about downloading "remove system tool", your virus protection should now be able to catch it and quarantine it.
Cheers, hope this helps.