There is no disk in the drive ccleaner

Hi, was at work this morning, with so much application installed in my computer, I decided to remove some which is not useful to me, after I removed those application, I run Ccleaner to clear all registry that might be left by the removed applications, when I run Ccleaner an error message appeared in my screen, please see below the screen shot of the error.
Piriform CCleaner: CCleaner.exe – No Disk
There is no disk in the drive. Please insert a disk into drive E:
When I saw the error message, I am wondering why it is looking upon some drives, since I am only working on registries, please share some points on why Ccleaner is acting like this, and some solutions for this issue.
Thanks.
