What operating system are you using? Normally one "associates" a program with an extension/file type, not "disassociates." If you associate a different program, that will stop Fireworks from launching as the default. But the steps to follow depend on your OS.
I am using Windows XP.
I use AcDSee as my default image viewer...jpg, jpeg, bmp, png, tif, etc are automatically opened with AcDSee. I'm happy with this.
When I "right click" an images icon, I get a menu that offers the choice of "Preview".
Previously to loading Fireworks, when clicked, this "Preview" function would launch the image file in Microsoft's "Window Picture and Fax Viewer"...now this same function ("Preview") opens the image in Fireworks which is slower to load than even AcDSee. (And to reinterate, AcDSee is still my default image viewer...not Fireworks)
I would like to re-gain this previous respective relationship with AcDSee and Windows Picture and Fax Viewer and knock Fireworks out of the loop completely. I can use an "Open With" function on the same "right click" menu when I want to open an image in Fireworks.
The problem is that I can find no way to get rid of Fireworks glomming on to this "right click" menu's "Preview" function. Fireworks gives me the option of making it my default viewer which I do not want. While AcDSee is my default viewer, Fireworks still hogs up this "Preview" function and I can find no option for switching it back to Widows Picture and Fax Viewer other than uninstalling Fireworks...which I do not want to do since it is a fine program for editing images; just too slow to view.
I hope this is more clear and I hope someone can help me figure this out.
Ah, I understand, now!
This problem isn't (exactly) a Fireworks problem, it's an XP configuration problem. I have Vista and Win2k, so I can't poke around one of my boxes, sorry.
Possible help in this thread, as the issues seem similar: http://www.tomshardware.com/forum/49577-45-windows-picture-viewer
There may be an answer here, but you'd have to sign up for a 30-day trial to find out:
Other than that, I would recommend posting your question on one of these two sites (which you'd have to join, but at least they're free):
http://www.majorgeeks.com/ (click the Support Forum link under Info on the right-hand side)
Sorry I couldn't be of more help.