Error when using YUILoader with container

When I use the YUILoader to load the container library and in the
"onLoadComplete" create a Dialog (it does not matter if I create it
from script or from markup) and afterwards "render" the dialog I get
this error in Firefox:

Component returned failure code: 0x80470002 (NS_BASE_STREAM_CLOSED)
[nsIScriptableInputStream.available]

The same error does not occur if I load the library manually (In the
head with <script> tags...
From what I can digest off the net it is a timing error?