Unexpected shutdown of SmartUPS 1500

[Anonymous user]

OK, I'm stumped.

I am an IT consultant working with a small design firm. They are running Windows Server 2008 r2 (x64) on a new (< 8 months) Dell PowerEdge T710. The server and critical network equipment (i.e., cable modem, network switch, monitor) are plugged directly into an APC SmartUPS 1500 (LCD) which was purchased in November of 2009 and had the battery replaced in Jan 2011 (faulty battery, replaced gratis by APC). Some other peripheral equipment (e.g., USB hard drives, wireless access point) are plugged into a power strip that also connects to the UPS.

With the exception of the battery that went bad, the unit has been up and operational nonstop for close for 16 months. Stable as a rock it was. Until yesterday. Sunday. When my client had an office full of folks working on a deadline. Without provocation of any type that we can figure, the UPS initiated a server shutdown and turned itself off. Here is the information from the Windows event log:

The process D:\Program Files (x86)\APC\PowerChute Business Edition\APC\PowerChute Business Edition\agent\bin\shutdown.exe (SERVER) has initiated the shutdown of computer SERVER on behalf of user NT AUTHORITY\SYSTEM for the following reason: Legacy API shutdown
Reason Code: 0x80070000
Shutdown Type: shutdown
Comment:

The Event Source was USER32 and the EventID is 1074.

After the server shut down, I suspect the UPS turned itself off as all of the peripheral equipment was reported to be powered down as well. The only indication that anything was happening was a single beep from the UPS. After about an hour, my client plugged everything directly into wall outlets and everything came back up. Fortunately, no data was lost that we know of. However, she is apoplectic that this happened and is, rightfully so, scared stiff that it may happen again.

The error above is the only indication in the Windows event logs that anything was amiss. PowerChute reports voltage in range over the entire period in question and no power events show up under any time frame. Risk assessment is low.

Any clues anyone? Scouring the web shows other folks have experienced this phenomena but I can find nothing close to a solution (not including "are you sure you don't have shutdown as a scheduled task?").

Any and all help is appreciated,
Bruce