symbol name error for instance db

Hi all

I have a weird problem,


I am using step7 v 5.4 sp5


when i create a instance db for a block i do not have any problem


but when i give a symbolic name to that db the following message appears

"access to instance data block by means of a global data block access is not allowed"

i have attached a screen shot for that too....

i have even tried to open my old project it also has the same problem.

But when i copy the project to another system there is no problem.

This problem started when i installed microsoft update.


but i am unable to find out which one is causing the problem

please tell me what i have to do.......