You can't even start the client?
Maybe because your dekaron.exe has been removed somehow...? Check it in the bin folder.
If you use NOD32, sometimes dekaron.exe will be removed without NOD32 even telling you.
So go to the control center, then "Carentine" (Can't remember how to spell it) and take the file back to it's orginal folder. Then turn off the "AMON" protection, no need to turn off the whole antivirus.
As i said, this is only if you're using NOD32.
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Now I'm heading back home to Sweden! I'm in Croatia (Hrvatska! :D) at the moment. (I hope Germany will be safe. I've heard it's a little like chaos? =/ o.O)
See you later people! :D