Does this only happen on a particular web site? I wonder whether the site might be using a Flash uploader. If you have any add-ons that block Flash, try unblocking that site.

Any luck? If not, would you want to post the URL?

(Also, I think there is a new Flash version available.)

Thanks for your time. On this reply page I can click "Browse" to upload a file without problem. I don't believe I have any add-ons that block flash. Shockwave flash is updated. Website is PayFlex.com. I've compared the Firefox settings on my mac to the Firefox settings on our other mac and can't find any differences. The other mac using Firefox again allows the file upload without problem on PayFlex.com. I have Apple support, do you think they may help trouble shot? Again, thanks for your time! Peter

I think you might want to submit an inquiry to PayFlex. (I suspect I can't get to the same form you're using...)

One other thing you could look at would be the Error Console. On Windows, this is on the Tools menu. Upon opening, there will be tons of messages. Click the Clear button, then reload the page where you are having a problem. Check for any errors (ignore warnings for now): these could indicate problems with setting up the functionality of the page. Then try the nonfunctional button and check for any more errors. The messages probably won't be helpful to you directly but might be helpful to PayFlex. Or Apple, if they are inclined to help. (They might just suggest using Safari!)