If you are signed in, there is a "Reply" with an arrow to the left of it under each post in the thread.
The key to seeing the "Reply" at the bottom of the message to which you want to reply is to be signed in.
Sometimes I find the I get mysteriously signed off and wonder what happened to the Reply button.
Check, scroll upward if necessary, the top right of the Forum page where it should show Welcome, followed by your user name. If you see that you are signed in.
Looking forward to your follow ups in your other thread.
go to http://forums.adobe.com/thread/1357922 and, as said, make sure you are logged in to the forum... which seems to be logging ME out about every half hour so I have to click the LOG IN option again
ignore previous email...I found the location for preview file clean up at documents/adobe. thanks...