Hi EastNets,
I tried locally but there is no problem with uploading attachments in datasheet view using IE 8. What’s the size and type of the file you want to upload? Can you upload it in the default view? Note that the default upload size limit is 50 MB. If you want to increase the size, follow this article. Try to upload another file which is a word file with small size to see if this will work.
If this is not your issue, check the event viewer and ULS logs to see if there is any error message. Detailed steps to reproduce this problem will be appreciated.
Let me know the result if possible, thanks.
Lu Zou