To mount an image or CD drive correctly you must add
-t cdrom
In your case it would be:
mount d e:\ -t cdrom
Remark: as usual in Dos times it's highly recommended to mount your drive/image as D not as E, will avoid problems with (mostly) early CD games.
Drive letters assigned in dosbox have nothing to see with the real Win drive letters.
Remark²: dosbox has an almost perfect working
imgmount command to mount images directly.
imgmount d x:\folder\name.iso -t cdrom
or
imgmount d x:\folder\name.cue -t cdrom
Remark³: If you're on Win7 you really should avoid c:\oldgames but use a folder in your own user folders, will avoid all kinds of read/write unpredictable restrictions.
http://www.abandonia.com/vbullet/showthread.php?t=22241