be careful with Dropbox

Today I installed Dropbox on my PC, using their installer.
Dropbox installed and immediately started to backup my Desktop folder (I had no intention to backup anything). On the desktop were a number of video files.
After a short time I was noticed that my 2 Gb free volume was full. There was no option to stop the backup. so my only option was to uninstall Dropbox. After a restart my desktop was empty. It appeared that I or my PC did not have anymore access to the Desktop folder. When I put a testfile on my desktop and I restarted the PC, that file was also gone. I felt that even after uninstalling Dropbox, it still hijacked my system. I was not able to correct things. My only option was to recover my system with a Macrium image file, which happily was available.