As quoted from an eminent Swedish Radio Journalist (hereby known as Deep P6 - as our source)
"A press conference with Svante and the EBU has just finished after the results of the Semi final were changed due to voting errors.
The 10 finalists are not affected, but some of the placings in the 11 to 22 range were changed. Israel now came 11th for example.
The cause of the problem was Monaco and Croatia.
In Monaco's case they didn't register a single televote, and the computer system broke down and made up a fake result. They are not sure why there were no votes but they think there was a technical error and the lines weren't opened.
In the Croatian case the sms votes tried to give Croatia 4 points and the mistake wasn't caught by the Croatian Telecom provider.
A new rule has therefore been introduced. Each televote in each country has to receive at least 100 votes in order for it to be valid. Otherwise the jury votes are used instead.
Svante & Co looked very tired, they've been up all night poor dears."
Make of it what you will!!
EDIT: Follow-up explanation (quoted from esctoday.com)