I checked with http://ip-check.info and I got this warning. When I did tested with that site, this never occurred until now. I didn't install any other addons or plugins in Tor Browser Bundle. I only have some bookmarks in the bookmarks bar. This warning makes scary! Please help.
Did you do what the message suggests, i.e. perform the test in order to get more details?
It's possible that the IP address uncovered by FTP isn't your address, but a secondary IP address associated with the exit node you were using at the time. In this case, the warning would be a "false alarm".
It's impossible to diagnose what is happening here without more information. Next time this happens, you need to a) perform the ip-check.info test and make a note of which IP addresses it claims to have "uncovered". b) Determine what exit node you are currently using. You can do this by visiting https://check.torproject.org/ which will show you the IP address of the exit node, and provide a link to Atlas with more information about the node. c) Determine what your "real" public-facing IP address is, e.g. by visiting a site like https://www.whatismyip.com/ with a browser other than Tor Browser. Then you can compare the IP addresses from a) b) and c) and see what IP address ip-check.info has found. Note that tor creates new circuits periodically (~every 10 minutes), so you need to do a) and b) in quick succession in order to get meaningful information.
The site says that it uncovered your IP address by FTP. This usually happens when you're not using SOCKS or HTTP proxy for all connections. Open the settings of Tor Browser (Green Onion -> Settings). Best is to use the recommended settings. If this is somehow not possible, make sure that FTP uses the same proxy as your other anonymized connections