Disabling Microsoft Security Essentials (the only anti-virus I have) did the trick for me. Which processes should I exclude to prevent this from happening again?

I have the same problem, I think it started on Monday. The connection is ok in eSignal Data Manager and I'm running eSignal just fine, but the charts in MultiCharts are blank and stuck on "Waiting for data" or "Establishing connection... (RT: Online)".

Please close Multicharts and all its products (i.e. MC, Quote Manager, PL editor, ....). Make sure that all MC processes are ended. In the Windows Task manager check these processes: atCenterServer.exe Fixserver.exe MultiCharts.exe MessageCenter.exe PLEditor.exe QuoteManager.exe StudyServer.exe tsS...