Miktex 2.9, Win 7: installing packages fails

Two problems have just arisen, after many happy years using MikTex:

1)  I have it set to install missing packages on the fly.  It stopped
working: when it finds a missing package, it just stops.

2)  If I try to install a missing package using package manager, it starts
to install, then it stops with this error message:
---------------------------------------
MiKTeX Problem Report
Message: Windows API error 5: Access is denied.

Data: C:\Program Files\MikTex2.9\fonts\afm\bitstrea
Source: Libraries\MiKTeX\Core\win\win.cpp
Line: 2686
MiKTeX: 2.9
OS: Microsoft Windows 7 Home Premium Edition, 32-bit Service Pack 1 (build
7601)
Invokers: Dropbox/explorer
SystemAdmin: no
PowerUser: no
Root0: C:\Users\David\AppData\Roaming\MiKTeX\2.9
Root1: C:\Users\David\AppData\Local\MiKTeX\2.9
Root2: C:\Program Files\MikTex2.9
Root3: C:\ProgramData\MiKTeX\2.9
Root4: C:\Program Files\MiKTeX 2.9
UserInstall: C:\Program Files\MikTex2.9
UserConfig: C:\Users\David\AppData\Roaming\MiKTeX\2.9
UserData: C:\Users\David\AppData\Local\MiKTeX\2.9
CommonInstall: C:\Program Files\MiKTeX 2.9
CommonConfig: C:\ProgramData\MiKTeX\2.9
CommonData: C:\ProgramData\MiKTeX\2.9
--------------------------------------------------

I uninstalled MikTex, reinstalled the basic package using the latest
version from the website, same problem.  Restarted the pc, didn't help.

thanks in advance for any help,
David
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