Have you tried in firefox safe mode?

yes, still doesn't do anything

That would mean a bad firefox install or update.

1. backup bookmarks 2. download latest firefox 3. uninstall all firefox install 4. delete mozilla folder 5. reinstall firefox 6. run firefox and see if the problem remains.

cactuschef said

When I try to download attachments such as a jpeg in gmail messages, nothing happens. I click the download button and nothing, no download is started / nothing in the downloads menu.

I've tried starting firefox with addons disabled, no effect.

Works fine in chrome/IE, can save pictures from other sites no problem.

Please do the following:

Click on the Windows icon 'Start' (bottom-left) and in the right column, bottom, click on Run. Enter in:

...Wait until the green bar loads and disappears, then click "Save All Information".
Post back here in the Forum, just these information parts, under these three Headers:

    System Information
 
    Display Devices
  
    Disk & DVD/CD-ROM Drives
 

~Pj