A week ago, we started to experience video flashing on some Windows 7 Enterprise computers running UltraVNC Server 1.0.8.2 as a service when UltraVNC Viewer clients (same version) are connected. The flashing stops on the server computer when the clients disconnect.
Does anyone have suggestions on what introduced the symptoms (e.g. Windows Updates, recent Microsoft Silverlight 4.0.60310 installation)? The computers have been running without these symptoms for over 8 months, and we make limited changes to the computer software (Windows updates, anti-virus updates, Office 2007 to 2010 upgrade one month ago).
Thanks for any assistance you can offer.
Symptoms
- When clients (even only one) connect to affected server computers, the server computer screen flashes intermittently (e.g. Word 2010 open, Internet Explorer 8 open). PowerPoint 2010 unexpectedly exits slideshow mode repeatedly while changing slides when clients are connected.
- When server computers are in this abnormal state, the UltraVNC and Network icons display as blank spaces in the Windows 7 Notification Area (System Tray). We haven't experienced the symptoms when the icons display normally.
- When all clients disconnect, the video flashing symptoms disappear.
- Affected server computers don't exhibit any obvious video (or network) issues when clients are disconnected. The Windows Event Logs don't appear to report any significant errors.
- All symptoms disappear (video flashing, missing Notification Area icons) after we restart affected computers, however they might reappear later on the same computer. It's not obvious what triggers the computer to enter this abnormal state. We haven't found a way to enter this state on demand.
Computer specs
- Windows 7 Enterprise 64-bit.
- All computers are built using the same image, with the same Group Policies applied.
- Users operate the server computers as non-administrators.
- UltraVNC Server 1.0.8.2 32-bit runs as a service.
- Computers are set to enter Sleep mode after 2 hours. It's unclear if the symptoms appear only after resuming from Sleep.
- UltraVNC Server is configured to disable Windows Aero (and switch to Windows Basic) theme when clients connect.
- I've enabled debug logging on previously affected computers (DebugMode=2, DebugLevel=10) to capture any useful data.
- Settings are applied using an ultravnc.ini file as follows:
Code: Select all
[Permissions]
[admin]
UseRegistry=0
MSLogonRequired=0
NewMSLogon=0
DebugMode=0
Avilog=0
path=C:\UltraVNC
DebugLevel=10
DisableTrayIcon=0
LoopbackOnly=0
UseDSMPlugin=0
AllowLoopback=0
AuthRequired=1
ConnectPriority=1
DSMPlugin=
AuthHosts=
AllowShutdown=0
AllowProperties=1
AllowEditClients=1
FileTransferEnabled=1
FTUserImpersonation=1
BlankMonitorEnabled=1
BlankInputsOnly=1
DefaultScale=1
CaptureAlphaBlending=0
BlackAlphaBlending=0
primary=1
secondary=0
SocketConnect=1
HTTPConnect=1
XDMCPConnect=0
AutoPortSelect=1
PortNumber=0
HTTPPortNumber=0
IdleTimeout=0
RemoveWallpaper=0
RemoveAero=1
QuerySetting=4
QueryTimeout=30
QueryAccept=0
QueryIfNoLogon=1
InputsEnabled=0
LockSetting=0
LocalInputsDisabled=0
EnableJapInput=0
kickrdp=0
clearconsole=0
FileTransferTimeout=30
KeepAliveInterval=5
[admin_auth]
group1=
group2=
group3=
locdom1=0
locdom2=0
locdom3=0
[ultravnc]
passwd=<REMOVED FOR POSTING>
passwd2=<REMOVED FOR POSTING>
[poll]
TurboMode=0
PollUnderCursor=0
PollForeground=0
PollFullScreen=1
OnlyPollConsole=0
OnlyPollOnEvent=0
MaxCpu=100
EnableDriver=0
EnableHook=0
EnableVirtual=0
SingleWindow=0
SingleWindowName=
