Unidentifiable alert to "cancel transfers"

About 3 months ago, I purchased a Dell XPS 13 running Windows 8. Ever since, whenever I try to shut down/restart my machine, I get an alert that looks like this:

This doesn't happen each time but it happens once in a while. The following is the sequence of events that produces this:

1. Using a web browser, for instance, Google Chrome (in deskptop mode). I close the web browser when I am done.
2. On the desktop, press ALT + F4 to bring up the prompt that let's you switch user or shut down and so forth.
3. Before the prompt comes up, I get the alert like the one in the screenshot.

I think this may be caused by something Microsoft Upload Center is doing but I'd like to know the exact cause.

Edit 1 : I have now noticed this happen independent of the usage of Chrome

Solution 1:

Note that when closing the web browser, it may actually still be running in the background.

Consider using the menu and doing Quit instead of closing the window.

This is particularly valid if you do large file transfers with your browser.

Alternatively I would look into the process tree for active processes or possible sources of such transfers.

Solution 2:

Your problem seems to be caused by SkyDrive and/or the Office "Save to Web".

See the article Disable Microsoft Office Upload Center and try it out, making sure that you can reverse all settings.

If this fixes the problem then this is a bug in SkyDrive.
You might try to :

1. find an alternate way of using SkyDrive not from inside Office
2. use another cloud storage than SkyDrive
3. do forcefully shut down the computer.