Excel macro security does not test for any virus, it only looks for active code module in the workbook. The warrning that a Virus may exsist is over dramatic. Some people think this protects them from bad code, if Excel security warns you that the workbook you are opening has code?
I use many levels of security as should everyone, FireWall, Virus checking-stopping software, spy-ware stopping software and pop-up blockers and others. I run code and do not as a rule download other peoples workbooks, So I turn Excel security off, by setting it to Low!
This way my code runs without a security message and does not stop open event code.
Try setting your security to low.
Excel ToolBar: Tools - Macro - Security, [Security Level] Low, [Trusted Sources] Trust access to the visual basic project, Should be Checked, also you should check-mark the Allow Addins, as well, or don't if you do not use then.
This should let your code work right?
If not then something is wrong, do you have your flashing code in the "Thisworkbook" code module as the Open Event, as it should be?