uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files and C:\Program Files(x86) Then restart system. Then run Windows Disk Cleanup. (Note: This should be Pinned and run Weekly, If never done below expect 10's of gig's) Then run it again and click the button that says Cleanup System Files. Note: your Firefox Profile is saved. But you should make a back up before you do :

• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles
• https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer

Reinstall with Current Release Firefox 57.0.2 with a Full Version Installer

• https://www.mozilla.org/firefox/all/

Please let us know if this solved your issue or if need further assistance.

Pkshadow said

uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files and C:\Program Files(x86) Then restart system. Then run Windows Disk Cleanup. (Note: This should be Pinned and run Weekly, If never done below expect 10's of gig's) Then run it again and click the button that says Cleanup System Files. Note: your Firefox Profile is saved. But you should make a back up before you do :

• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles
• https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer

Reinstall with Current Release Firefox 57.0.2 with a Full Version Installer

• https://www.mozilla.org/firefox/all/

Please let us know if this solved your issue or if need further assistance.

I will not even try this because this issue appears not only on my machine but only for a one web site (which I develop). I think it is more about bug in Firefox functionality because it works perfectly in other web browsers. I've attached screenshot with files that I've downloaded. I can share js code which downloads .zip file if it will be helpful.

Firefox immediately starts downloading the file in the background and saves the .part file to the temp folder and doesn't wait until you specify the name and the location (destination folder). If the file stays in the temp folder then it is possible that your security software is blocking the file and prevents Firefox from moving the file to the specified destination folder and rename the file to the correct file extension.

Try to disable your AV software during the download and installation and start the Firefox installer via the right-click context menu and Run as: Administrator.

cor-el said

Firefox immediately starts downloading the file in the background and saves the .part file to the temp folder and doesn't wait until you specify the name and the location (destination folder). If the file stays in the temp folder then it is possible that your security software is blocking the file and prevents Firefox from moving the file to the specified destination folder and rename the file to the correct file extension. Try to disable your AV software during the download and installation and start the Firefox installer via the right-click context menu and Run as: Administrator.

In this case AV software will block each file I trying to downlad but not only one of 10 or something. Anyway if you will take a look at the screenshot you will see that .part file placed in the same folder that other .zip files, so Firefox already moved .part from temp folder to destination folder.

W3C.org *World Wide Web Consortium ) Who make the rules for web code, practices and standards and future of development of web page code and web browsers.

• HTML https://validator.w3.org/
• CSS https://jigsaw.w3.org/css-validator/
• https://validator.w3.org/i18n-checker/
• http://mobile.css-validator.org/

Start again and this time supply the web address you did not supply. Like give the information as it really prolongs this whole thing when it is really unneeded if give the info in the 1st places. Do You really want to make a 2nd page..or 3rd I will not answer you again as you can not give information that will help with helping you.