1. Yes, the error occur even for blank excel workbook.
2. Yes, excel was working fine before.
3. I just did microsoft window update (Security update for SQL server 2005 SP3 KB970892 could not update, failed and tried many time), didnt install any other program so far.
4. Counter check all add-in, by default is all UNCHECKED.
5. No written or saved any macro. Sometime open email attachment, will ask enable or disable, i chooses enable sometime, is that related?
Thanks a lot of your guide on this.