Error CNDP/005 when trying to log into a SAp System

Hello everyone,

when trying to log into a SAP System, i get the following dump:

Error analysis
    Short text of error message:
    Control Framework: Data stream error. Transaction terminated.

    Long text of error message:
     Diagnosis
         The data stream from the frontend could not be interprete
     System Response
     Procedure
         This error is very probably due to an error in the fronte
         software installation or an obsolete version. Inform your
         administrator.
     Procedure for System Administration
         The frontend should have at least the same version as the
         release. Install the correct frontend. If the error conti
         occur, inform SAP.

    Technical information about the message:
    Message class....... "CNDP"
    Number.............. 005
    Variable 1.......... " "
    Variable 2.......... " "
    Variable 3.......... " "
    Variable 4.......... " "

It occurs directly after inserting my User/Password and pressing enter.

My SAP GUI: Version 710, Patchlevel 11

The strange thing about that:

Last week i didn't have this error and i didn't change anything.

I already uninstalled, reinstalled and rebooted but it didn't work.

I would appreciate some help.