I had the same problem...
It is a virus in the AppData folder ... search for the file ... \...\plugin\8\plugin.exe
You need to remove it in Safe Mode ... so delete it in Safe Mode...
I know this because I use BitDefender 2015 and it told me its a virus and how to remove it.
After I removed this file and restarted ... I started the Metatrader 4 and it worked normally.
Its a Virus that BitDefender 2015 finds in
ProgramData\3929cb63-cbbd-4b9c-8b92-a50fbd04e656\...\plugin\8\ some exe file
Remove it in Safe Mode and you are good to go.