Error message when combining PDF's
I'm receiving an error message when I try to combine PDF's. I combine files daily so I'm not sure what the problem is. This has been happening on and off for 3 days. After I drag and drop PDF's in order to combine, I click to download and an error pops up that says "there is an operation already in use" but in reality there is no prior operation in use. I also see at the same time the combining download icon circulating idle non-stop. I log off and log on to acrobat and have tried Mozilla, Internet Explorer and Chrome but the same issue happens. Help!
