1. Make sure you are using the latest version of IDM
Please use "Help→Quick Update" IDM main menu item to get the latest version of IDM installed or download it from our site.
2. If you have a premium account on the file sharing site
a) You need to add your login and password for this site in "Options→Sites Logins" dialog. You need to add two entries. Use "sitename.com" and "*.sitename.com" as server names:
b) Please also log into the Premium Zone of this site, search for something like "Direct Download" or "Direct Link" and enable this option. Our users who had similar problems reported that this helped them. Look at the examples below:
c) If you add your downloads using drop target, batch download from clipboard, using lists in text files, etc. then you should open Internet Explorer (exactly Internet Explorer, and not another browser, independently of what browser you are using for browsing the Internet) and log in on the site as a premium user. If login form has "remember me" box, please tick it as well. The site will set cookies in Internet Explorer which IDM is able to use when you add the downloads to IDM. Afterwards you can close IE.
d) Also maybe your premium account expired. Or this can happen if your daily download limit expired. When IDM starts downloading HTML files, you need to try to login in your account and check that everything is in order. Also you can try to download a file with browser. IDM should not catch the download, and you should see web page with explanation of this problem.
e) Some sites have weird problems when several files are requested at the same time by the same visitor, the premium account is turning off. For such sites add downloads to a download queue in IDM. You may create a new "one-time downloading" queue especially for each site. Then right click on queue name in the main IDM window, choose "Edit queue" and set "Download 1 file at the same time". Afterwards run the queue.
f) Please note that in some cases downloads which have been started in old versions of IDM (earlier than 5.19), may not be able to finish. Unfortunately you will need to delete such downloads and add them again in a new version of IDM.
3. If you have free account on this site
You need to enable "Start downloading immediately while displaying..." option in "Options→Downloads" dialog (if it is disabled). Also please note that if you have a free account, IDM will download correct file only when the download is captured automatically from your browser. If you use "Download with IDM" browser context menu item or download panel for selected links, IDM will download a web page instead of a download.
4. If you use FireFox
In such case problems may happen if you use extensions from third party companies to transfer download in IDM, for example Flashgot. IDM can perfectly detect downloads itself but if you really want to use Flashgot, at least update it to the latest version.