Server generated CSV attachment, when opened in Excel has weird sheet name

I have my server generate and outputs csv file which the browser then pops up a open/save dialog.

When I open it up, all is well except the sheet name. The sheet name is mangled. If my filename is CsvData.csv for example, then let's say I 开发者_运维知识库download it several times, you'll eventually see the sheet name turn into something like:

.csv]CsvData(2)

I mean the sheet name can be changed and saved which is not a problem but this seems strange. This is in IE 6. In firefox, I get names like CsvData-1, CsvData-2, etc.

I'm guessing this can't be controlled. Anyone?