This is a problem I’ve been having for several months: Sometimes, upon booting my 64-bit Vista desktop machine and logging in, I get one of those taskbar balloons that tells me that “Windows could not connect to the System Event Notification Service,” and some other stuff about because of this, non-admin users will not be able to log in, and I should check the event log for details. This seems to happen to me almost without fail after I had installed some Vista software updates and rebooted from that installation (I guess since that seems to jog up the order that things happen in at boot time), but anyway, it was not exclusive to that, although it would almost always be fine after I rebooted again.
Since I’m an administrative user (and there’s only one account on my machine), there seemed to be nothing else wrong after the notification went away. The System Event Notification Service is running, even. Still, errors like this are somewhat disturbing.
Anyway, I Googled around a little and found little useful information; however, I believe I have fixed it on my machine.
If you are having this problem (errors but the service seems to be working fine), here’s what to try:
Go to regedit, and navigate to: Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SENS.
Change the value of “Start” from 0×00000002 to 0×00000001. This is a trick I’ve used on services before, it pretty much makes this service start earlier, before other services that are set to start “Automatically.” This is to help make sure that the service is up and running before something else tries to connect to it and decides that its not working, and throws up this error.
Since then, I haven’t had this notification pop up; however, it’s difficult to test since it happens sporadically. I’ll update this post if I learn anything else.