Jon,

I have solved my problem by inserting string strA = strB.Trim( ) statement
between several lines of code until I have pinpointed exact place where
"Trim( )" method starts failing.

The reason was an incorrect declaration of "GetPrivateProfileString" API -

[DllImport("kernel32.dll", CharSet=CharSet.Unicode, SetLastError=true,
EntryPoint = "GetPrivateProfileString", CallingConvention =
CallingConvention.StdCall )]
    public extern static int GetPrivateProfileString( string section, string
key, string default, [Out, MarshalAsAttribute(UnmanagedType.LPTStr)] string
buffer, ref int size, string fileName );

which I used in the following way -

    string fileName = "C:\\Windows\\file.ini";
    string buffer = String.Empty;
    int size = 0;
    size = GetPrivateProfileString( "Section", "Key", "Default", buffer, ref
size, fileName );
    version = new string( '\0', size );
    GetPrivateProfileString( "Section", "Key ", "Default", buffer, ref size,
fileName );

After the last call the "buffer" variable did contain correctly read value
but all subsequent calls to String.Trim( ) method began to throw
‘ExecutionEngineException’.

Now I am using the following declaration -

    [DllImport("kernel32.dll", CharSet=CharSet.Unicode, SetLastError=true,
EntryPoint = "GetPrivateProfileString", CallingConvention =
CallingConvention.StdCall )]
    public extern static int GetPrivateProfileString( string section, string
key, string default, IntPtr buffer, ref int size, string fileName );

I would appreciate if you briefly explained what was wrong with the
declaration I had used in the first place.

Thank you for your help.

Eugene.