Can not open Comsol with "An unexpected error occurred"

hi everyone

Yesterday, I used Comsol normally, but today I can not open it anymore. It gives me this error and its details:

"An unexpected error occurred."

'.', hexadecimal value 0x00, is an invalid character.
at System.Xml.XmlEncodedRawTextWriter.InvalidXmlChar(Int32 ch, Char* pDst, Boolean entitize)
at System.Xml.XmlEncodedRawTextWriter.WriteElementTextBlock(Char* pSrc, Char* pSrcEnd)
at System.Xml.XmlEncodedRawTextWriter.WriteString(String text)
at System.Xml.XmlWellFormedWriter.WriteString(String text)
at System.Xml.Linq.ElementWriter.WriteElement(XElement e)
at System.Xml.Linq.XElement.WriteTo(XmlWriter writer)
at System.Xml.Linq.XNode.GetXmlString(SaveOptions o)
at Comsol.Command.BridgeCommand.ToCommandString()
at Comsol.Communication.ChannelBasedCommandManager.SendCommand(OutgoingCommandHandler commandHandler)
at Comsol.Communication.BridgeCommandManager.OutgoingCommandHandler.Run()
at Comsol.Communication.BridgeCommandManager.RunAndWait(BridgeCommand command)
at ComsolDesktop.MainWindow.StartJava(Boolean debug, Boolean devPlugins, NDisconnectInfo disconnectInfo, IBridgeCommandManager oldMgr)
at ComsolDesktop.MainWindow.StartJava(Boolean debug, Boolean devPlugins)
at ComsolDesktop.App.OnStartup(StartupEventArgs e)
at System.Windows.Application.<.ctor>b__1(Object unused)
at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)

is there anyone has some ideas about this problem ?
Many thanks
Duc