In IE 7 the "auto-copy" function is disabled by default - but in older IE browsers, it's enabled by default.

If you are getting the message in IE7:

"Do you want to allow this webpage to access to your clipboard?"

See this thread for insight & a solution:

http://radified.com/cgi-bin/yabb2/YaBB.pl?num=1174844463/12#12

Or .. basically, the short version:

Ad Radified.com as a 'trusted' site by:
Tools > Internet Options > "Security" tab > (Click on) "Trusted sites" (Green check-mark) > "Sites" button > Select "Ad this website (Radified.com) to the zone: "

and then enabled "Allow Programmatic Clipboard Access" by ...

clicking "Custom level..." button (which is also located on the "Security" tab)
should now say at top > "Security Setting - Trusted Sites Zone"

Scroll way down (near the bottom) to
"Allow Programmatic Clipboard Access",
Click Enable.
Click OK.
 
Viola!

PS - you can also disable the access, but it comes in handy to have your post (automatically) copied to your clipboard .. should anything go wrong. I have twice already taken advantage of this feature.

PSS - There is also a forum-based fix/patch for this, but I have not installed it (yet?):

http://www.boardmod.org/yabb/YaBB.pl?board=beta_y2;action=display;num=1165506700

http://www.google.com/search?q=allow+this+webpage+to+access+to+your+clipboard