Often WinDbg will enter a state where it is *Busy* performing an operation.
Often this is due to some mistake I made trying to *dt some_variable_itll_never_find* or setting a break point somewhere without symbols or the 1000's of other mistakes I make fumbling around this tool.
Is there a way to cancel the current operation?
I don't have the tool now, but as far as I remember it should be Ctrl+Break.
You probably had "http://msdl.microsoft.com/download/symbols" in the symbol path.
Windbg will try to locate all your PDBs on Microsoft site :-(.
Pressing Ctrl+Break is not fast enough.
What I usually do is to unplug the network cable, until Windbg wakes up.
Just be carfull, if Windbg was realy downloading one if its OS DLL, the DLL gets curropted. You will need .reload /o to fix that DLL. I only unplug when I know all OS DLL were already downloaded.
To avoid this delay in the first place, uncheck "Resolve Unqualified Symbols" found under the "Debug" menu.