Windows Vista ["Unpacking Data" message on start-up]

The past few weeks I get and "unpacking data" message every time I log into my computer. It seems to give the message twice along with a % of data unpacked; I guess. It doesn't seem to cause any trouble except for a few seconds delay in getting on with my work. I saw on e thread on the subject but it was not useful. Does anyone have an idea about where this came from and why it is dong it?

 

The "unpacking data" message stopped without any action by me. I think it must have been something corrected by a Windows update but I don't know for sure.